Refrigerant compressor, and refrigerating machine using the same

ABSTRACT

A refrigerant compressor includes a compressor section, driver, a first contact section and a second contact section. The compressor section is accommodated in a closed container for compressing refrigerant gas. The driver drives the compressor section. The first and second contact sections are brought into contact with each other or they slide with each other by driving the compressor section. On the surface of each one of the contact sections, at least one of plural recesses uniformly placed or a mixed layer, to which molybdenum disulfide (MoS 2 ) is bound, is formed. The foregoing structure allows increasing the abrasion resistance of the first and second contact sections.

This Application is a U.S. National Phase Application of PCTInternational Application PCT/JP2003/016023.

TECHNICAL FIELD

The present invention relates to refrigerant compressors to be used inrefrigerators and air-conditioners, and refrigerating machines using thesame refrigerant compressor.

BACKGROUND ART

A recent glowing tendency in the global environment protection has urgedthe industry to develop efficient compressors consuming less fossilfuel.

FIG. 58 shows a sectional view of a conventional electrical enclosedrefrigerant-compressor. FIG. 59 illustrates a supporting structure forthe compressor. Closed container (hereinafter referred to simply as“container”) 1 pools oil 2 at the bottom, and accommodates motor section5 having stator 3 and rotor 4, as well as compressor section 6 driven bymotor section 5. Compressor unit 7 having motor section 5 and compressorsection 6 is resiliently supported by compression spring (hereinafterreferred to simply as “spring”) 8 in container 1.

Crankshaft 9 has main shaft 9A, to which rotor 4 is fixed, and eccentricsection 9B formed eccentrically with respect to main shaft 9A.Lubricating pump 10 is prepared to crankshaft 9. Main shaft 9A issupported by bearing 23. Cylinder block 11 has compressing room 13including typically cylindrical bore 12. Piston 14 goes back and forthin bore 12, and is coupled to eccentric section 9B with a slidingmechanism. An end face of bore 12 is sealed by valve plate 15.

Head 16 forms a high-pressure room. Discharging path 17, which guidescompressed refrigerant gas from head 16 to outside container 1, iscoupled via pipe 18 to a high pressure side (not shown) of arefrigerating cycle disposed outside container 1. Pipe 18 is made ofpolymer material of heat resistance, refrigerant resistance, and oilresistance. Pipe 18 prevents discharging path 17 from resonating.

Holder 20 made of synthetic resin is mounted to a head of each one ofbolts 19 which fasten the stator of motor section 5. Another holder 22made of synthetic resin is mounted to each one of projections 21provided on the inner wall of container 1. Springs 8 are placedsurrounding holders 20 and 22.

An operation of the foregoing refrigerant compressor is demonstratedhereinafter. Commercial power is supplied to motor section 5 and rotatesrotor 4, which spins crankshaft 9, so that eccentric section 9Beccentrically moves to drive piston 14. The reciprocation of piston 14in bore 12 puts refrigerant gas guided into container 1 into compressorroom 13 via a suction valve (not shown). The refrigerant gas is thencontinuously compressed, and transferred outside container 1 via adischarging valve (not shown), discharging path 17, and pipe 18.

The rotation of crankshaft 9 prompts lubricating pump 10 to supply oil 2to respective sliding sections for lubricating the sliding sections, andoil 2 is discharged from a tip of eccentric section 9B into container 1.Oil 2 also works as seal between piston 14 and bore 12.

Main shaft 9A of crankshaft 9 and bearing 23 form a sliding section witheach other as well as piston 14 and bore 12. In the conventionalcompressor, a first member of the sliding section is made of nitridediron-based material undergone manganese phosphate process, and a secondmember thereof is made of aluminum die-cast undergone anodizing. Thosetechniques are disclosed in, e.g. Japanese Patent ApplicationNon-Examined Publication No. H06-117371.

However, if the sliding sections are processed by manganese phosphatewhich has a low hardness, the manganese-phosphate layer tends to wearaway when metallic contact occurs on the sliding section at theoperation start because oil film does not yet cover the sliding section.Then the friction coefficient becomes higher, and sliding loss possiblyincreases. A smaller clearance between the sliding sections fordecreasing the friction coefficient will produce metallic contact, whichwears the manganese-phosphate layer away, so that friction increases orabnormal friction possibly occurs. Further, between piston 14 and bore12, piston 14 wears much, so that the space in between becomes greater.As a result, compressed refrigerant gas may leak from the space betweenpiston 14 and bore 12, thereby lowering the efficiency.

On top of that, use of the oil of low viscosity for lowering the viscousresistance will reveal the foregoing problems more expressly.

Another prior art discloses a compressor of which sliding sections areapplied with molybdenum disulfide (MoS₂), as solid lubricant on theirsurfaces. Such a compressor is disclosed, e.g. Japanese PatentApplication Non-Examined Publication Nos. H08-121361 and H09-112469.

MoS₂ includes a binder of polyamide-imidic resin (PAI) because it isapplied to the sliding sections; however, PAI has a higher frictioncoefficient than MoS₂, so that the sliding loss increases. In the caseof using metal such as iron or aluminum as base material of the slidingsections, those metals have binding force to the PAI (binder) weakerthan those of ordinal metallic bonds. At the sliding section on whichMoS₂ is applied, peeling occurs on the interface between the basematerial and the binder. As a result, MoS₂ cannot exert its advantage ofincreasing abrasion resistance, and yet, an amount of abrasive wearsometimes increases.

The linear movement of piston 14 excites compressor section 6, and thisexcitation always causes micro-vibration at spring 8 during the rotationof compressor unit 7. At the operation start or stop, compressor section6 largely wobbles due to inertia force, and then spring 8 also wobbles,so that spring 8 contacts holders 20, 22 intermittently, and they scrapeagainst each other. At this time, holders 20, 22 absorb the scrapingnoise since they are made from synthetic resin. Those techniques aboutcompressors are disclosed in Japanese Patent Application Non-ExaminedPublication No. H06-81766.

The foregoing structure, however, needs holders 20, 22 separatelybecause they are made from synthetic resin, so that the number ofcomponents and the manufacturing cost increase.

Since compressor section 6 largely wobbles at the operation start andstop, discharging path 22 also largely wobbles, so that path 22 contactspipe 23 intermittently, and they scrape against each other. The scrapingnoise is absorbed by pipe 23 because it is made of polymeric material.However, this material is expensive because of its heat resistance,refrigerant resistance, and oil resistance.

In the compressor, the valves (not shown) for sucking and dischargingthe refrigerant gas between compressing room 13 and container 1 operatefollowing the drive of compressor section 6. Then the valve portcontacts the valve seat, thereby producing noises.

As such, the drive of compressor section 6 entails various sections tocontact with each other or scrape against each other, so that theabrasive wear lowers the performance or produces noises. For overcomingthe foregoing problems, the prior art requires additional components orexpensive materials.

DISCLOSURE OF THE INVENTION

The refrigerant compressor of the present invention has a compressorsection, a driver, a first contact section and a second contact section.The compressor section is accommodated in a closed container forcompressing the refrigerant gas. The driver drives the compressorsection. The first and second contact sections contact with each otheror slide against each other due to the drive of the compressor section.On the surfaces of the contact sections, at least one of recessesuniformly placed or a mixed layer, to which MoS₂ is bound, is formed.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a sectional view of a refrigerant compressor in accordancewith an exemplary embodiment of the present invention.

FIG. 2 shows an enlarged view of a sliding section formed by a pistonand a bore shown in FIG. 1.

FIG. 3 illustrates a flow of oil when the piston slides along the boreshown in FIG. 1.

FIG. 4 shows a refrigerating cycle of a refrigerating machine whichincludes the compressor shown in FIG. 1.

FIG. 5 shows locked pressures in accordance with the exemplaryembodiment of the present invention.

FIG. 6 shows friction coefficients in accordance with the exemplaryembodiment of the present invention.

FIG. 7 shows amounts of abrasive wear in accordance with the exemplaryembodiment of the present invention.

FIG. 8 shows an enlarged view of a sliding section formed by a mainshaft and a bearing shown in FIG. 1.

FIG. 9 shows an enlarged view of the vicinity of the piston shown inFIG. 1.

FIG. 10 shows an enlarged view of a sliding section formed by the pistonand a connecting rod shown in FIG. 9.

FIG. 11 shows an enlarged view of the vicinity of a thrust bearing shownin FIG. 1.

FIG. 12 shows an enlarged view of a sliding section formed by a thrustsection and a thrust washer shown in FIG. 11.

FIG. 13 shows characteristics of friction coefficient between a slidingface and a manganese phosphate layer in accordance with the exemplaryembodiment of the present invention.

FIG. 14 shows characteristics of refrigerating capacity of thecompressor in accordance with an exemplary embodiment of the presentinvention.

FIG. 15 shows efficiencies of the compressor in accordance with anexemplary embodiment of the present invention.

FIG. 16 shows a sectional view of another refrigerant compressor inaccordance with an exemplary embodiment of the present invention.

FIG. 17 shows a refrigerating cycle of the refrigerator which includesthe compressor shown in FIG. 16.

FIG. 18 shows a sectional view taken along line 18-18 of FIG. 16.

FIG. 19 shows an enlarged view of a sliding section formed by the vaneand the rolling piston shown in FIG. 18.

FIG. 20 shows an enlarged view of a sliding section formed by therolling piston and the eccentric section shown in FIG. 18.

FIGS. 21A and 21B show enlarged views of a sliding section formed by thepiston and the bore in accordance with an exemplary embodiment of thepresent invention.

FIG. 22 shows a flow of oil at the sliding section shown in FIG. 21B.

FIG. 23 shows friction coefficients in accordance with an exemplaryembodiment of the present invention.

FIG. 24 shows amounts of abrasive wear in accordance with an exemplaryembodiment of the present invention.

FIGS. 25A and 25B show enlarged views of a sliding section formed by themain shaft and the bearing shown in FIG. 1.

FIGS. 26A and 26B show enlarged views of another sliding section formedby the piston and the connecting rod shown in FIG. 1.

FIGS. 27A and 27B show enlarged views of another sliding section formedby the thrust section and the thrust washer shown in FIG. 1.

FIG. 28 shows characteristics of friction coefficients in accordancewith an exemplary embodiment of the present invention.

FIG. 29 shows characteristics of refrigerating capacity of thecompressor in accordance with an exemplary embodiment of the presentinvention.

FIG. 30 shows characteristics of efficiencies of the compressor inaccordance with an exemplary embodiment of the present invention.

FIGS. 31A and 31B show enlarged views of another sliding section formedby the vane and the rolling piston shown in FIG. 16.

FIGS. 32A, 32B show enlarged views of another sliding section formed bythe rolling piston and the eccentric section shown in FIG. 16.

FIG. 33 shows a vertical sectional view of a sucking valve devicedisposed in the compressor in accordance with an exemplary embodiment ofthe present invention.

FIG. 34 shows a plan view of a valve port of the sucking valve deviceshown in FIG. 33.

FIG. 35 shows a plan view of a sucking valve of the sucking valve deviceshown in FIG. 33.

FIG. 36 shows a vertical sectional view of a discharging valve devicedisposed in the compressor in accordance with an exemplary embodiment ofthe present invention.

FIG. 37 shows a plan view of a valve port of the discharging valvedevice shown in FIG. 36.

FIG. 38 shows a plan view illustrating a side of mutual sealing face ofthe discharging valve in the discharging valve device shown in FIG. 36.

FIG. 39 shows a plan view illustrating a striking section side of adischarging movable valve of the discharging valve device shown in FIG.36.

FIG. 40 shows a plan view of a stopper of the discharging valve deviceshown in FIG. 36.

FIG. 41 shows a vertical sectional view of another discharging valvedevice disposed in the compressor in accordance with an exemplaryembodiment of the present invention.

FIG. 42 shows a striking section side of the discharging movable valveagainst the backup lead of the valve device shown in FIG. 41.

FIG. 43 shows a striking section side of the stopper against the backuplead of the discharging valve device shown in FIG. 41.

FIG. 44 shows a plan view of another sucking valve port disposed in thesucking valve device shown in FIG. 33.

FIG. 45 shows a plan view of another sucking movable valve disposed inthe sucking valve device shown in FIG. 33.

FIG. 46 shows a plan view of another discharging valve port disposed inthe discharging valve device shown in FIG. 36.

FIG. 47 shows a plan view illustrating mutual-sealing-face side ofanother discharging movable valve in the discharging valve device shownin FIG. 36.

FIG. 48 shows a plan view illustrating a striking section side ofanother discharging movable valve of the discharging valve device shownin FIG. 36.

FIG. 49 shows a plan view of another stopper of the discharging valvedevice shown in FIG. 36.

FIG. 50 shows a striking section side of another backup lead againstdischarging movable valve of the discharging valve device shown in FIG.41.

FIG. 51 shows a striking section side of another backup lead against astopper of the discharging valve device shown in FIG. 41.

FIG. 52 shows a sectional view of still another compressor in accordancewith an exemplary embodiment of the present invention.

FIG. 53 shows a refrigerating cycle of the refrigerator which includesthe compressor shown in FIG. 52.

FIG. 54 shows an enlarged view illustrating a portion where the coilspring closely contacts a discharging path in the compressor shown inFIG. 52.

FIGS. 55A and 55B are enlarged views illustrating a portion where thecoil spring closely contacts another discharging path in the compressorshown in FIG. 52.

FIG. 56 shows a sectional view of yet still another compressor inaccordance with an exemplary embodiment of the present invention.

FIGS. 57A, 57B and 57C show enlarged views illustrating a portion wherethe compression coil spring contacts the holders in the compressor shownin FIG. 56.

FIG. 58 shows a sectional view of a closed electrical refrigerantcompressor developed by the prior art.

FIG. 59 shows a supporting structure of the compressor shown in FIG. 58.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Exemplary embodiments of the present invention are demonstratedhereinafter with reference to the accompanying drawings. In respectiveembodiments, elements similar to those of a previous embodiment have thesame reference marks, and the detailed descriptions thereof are omitted.

Exemplary Embodiment 1

FIG. 1 shows a sectional view of compressor 100 in accordance with afirst exemplary embodiment of the present invention. FIG. 2 shows anenlarged view of a sliding section formed by a piston and a bore shownin FIG. 1. FIG. 3 shows a flow of oil at the sliding section of thepiston and the bore. FIG. 4 shows a refrigerating cycle of arefrigerating machine that includes compressor 100. FIG. 5 shows lockedpressures in a state of having fine recesses or no fine recesses. FIG. 6shows characteristics of friction coefficients depending on the shapeand size of the fine recesses. FIG. 7 shows characteristics of amountsof abrasive wear depending on areas of the fine recesses on the surfaceof the sliding section.

In FIG. 1-FIG. 3, closed container (hereinafter referred to simply as“container”) 101 is filled with refrigerant gas 102 made of isobutane.Container 101 pools oil 103, accommodates motor section 106 havingstator 104 and rotor 105 as well as reciprocating compressor section 107driven by motor section 106. Motor section 106 works as a driver, and ifcompressor section 107 is disposed in container 101 airtightly, motorsection 106 can be prepared outside container 101.

Next, compressor section 107 is detailed. Crankshaft 108 has main shaft109, to which rotor 105 is press-fitted, and eccentric section 110eccentric with respect to main shaft 109. Crankshaft 108 has lubricatingpump 111 at its lower end, and pump 111 communicates with oil 103.Cylinder block 112 made from cast-iron forms typically cylindrical bore113 and bearing 114 which rotatably supports main shaft 109.

Piston 115 reciprocating in bore 113 is made from iron-based materialand forms compressing room 116 together with bore 113. Piston 115 iscoupled to eccentric section 110 with connecting rod 118 via piston-pin117. An end face of bore 113 is sealed by valve plate 119.

Head 120 forms a high-pressure room and is fixed on valve plate 119 atthe opposite side to bore 113. Suction tube 121 is fixed to container101, and coupled to heat-exchanger 60 at the lower pressure side of therefrigerating cycle for guiding refrigerant gas 102 into container 101.Suction muffler 122 is sandwiched by valve plate 119 and head 120, whichdischarges compressed refrigerant 102 to heat exchanger 70, whererefrigerant 102 dissipates the heat. Then refrigerant 102 returns toheat exchanger 60 via expansion valve 80 and collects heat. Therefrigerating machine is thus structured.

Sliding sections are formed between the following elements respectively:main shaft 109 and bearing 114; piston 115 and bore 113; piston pin 117and connecting rod 118; eccentric section 110 and connecting rod 118.Those elements forming the sliding sections are contact sections thatslide against each other due to driving compressor section 107.

On sliding face 115A of piston 115, fine recesses 123 are formed almostuniformly. Each one of recesses 123 is shaped like a sphere, andpreferably has a diameter of 20-50 μm, depth of 1-10 μm. The area ofrecesses 123 more preferably accounts for 40-80% of the surface area ofsliding face 115A. In the case of using iron-based material for theelements discussed above, the sliding faces thereof have preferablyundergone martensitic process.

Recesses 123 can be formed by etching or press-molding the surface. Inthis embodiment, hard micro-balls having a high hardness such as steelballs or ceramic balls crash to the surface at a speed higher than agiven one, thereby forming recesses 123. For instance, in the case ofincreasing the hardness of the cast iron by work-hardening, ceramicmicro-balls or steel micro-balls, having 2-50 μm diameter and a hardnesshigher than that of the subject item, are accelerated and injected froma projector, such that the balls have a speed of 20 sec/min, against thesurface of the cast iron. The collision at a high speed against thesubject item, as discussed above, provides the surface of the subjectitem with residual compressing stress, thereby increasing the hardnessup to about 600 Hv in terms of Vickers hardness.

An operation of compressor 100 thus structured is demonstratedhereinafter.

Commercial power is supplied to motor section 106, thereby spinningrotor 105 of motor section 106. Rotor 105 rotates crankshaft 108, andeccentric movement of eccentric section 110 drives piston 115 viaconnecting rod 118 and piston pin 117. Piston 115 thus reciprocates inbore 113. Refrigerant gas 102 guided through suction tube 121 intocontainer 101 is sucked from suction muffler 122 and compressedcontinuously in compressing room 116.

The rotation of crankshaft 108 supplies oil 103 from pump 111 torespective sliding sections for lubricating each one of the slidingsections and also for sealing between piston 115 and bore 113.

When the reciprocation of piston 115 in bore 113 compresses refrigerantgas 102, parts of compressed gas 102 leak into container 101 via a spacebetween piston 115 and bore 113, thereby lowering the volumetricefficiency. However, in this embodiment, the gas leaking to the spacebetween piston 115 and bore 113 reaches recesses 123, so that the volumeof the space between piston 115 and bore 113 increases. Recesses 123therefore work like the labyrinth seal, and the flow speed of the gasleaking lowers sharply. As a result, the volumetric efficiency ofcompressor 100 increases, and the compression efficiency of compressor100 increases.

Next, the measurement of the locked pressure is described with referenceto FIG. 5. The contact pressure is measured on the face having the finerecesses and the face having no fine recesses in the followingconditions:

-   -   atmospheric pressure in CH₂FCF₃ refrigerant; 0.4 MPa,    -   ester oil viscosity; VG8-VG10 of ISO viscosity grade, and    -   sliding speed; 1.0 m/sec

As FIG. 5 clearly tells, piston 115 having recesses 123 shows asubstantially better locked pressure than the piston having no recesses123. The formation of recesses 123 almost uniformly on the sliding faceallows recesses 123 to retain oil 103 supplied. When the space betweenthe sliding sections becomes smaller along the sliding direction, oil103 is drawn into the smaller space due to the viscosity of oil 103 andthe relative movement of the respective sliding sections. This mechanismproduces a pressure in oil 103 for supporting a load, so thatwedge-shaped oil film is formed. This oil film prevents the metalcontact from happening between the sliding sections, so that a higherlocked load can be expected.

The friction coefficient is measured using the shape and size ofrecesses 123 as parameters in the following condition:

-   -   atmospheric pressure in CH₂FCF₃ refrigerant; 0.4 MPa,    -   ester oil viscosity; VG8-VG10,    -   sliding speed; 1.0 m/sec, and    -   contact pressure; 0.5 MPa

The result tells that piston 115 with spherical recesses 123 has thefriction coefficient lower than that with angular recesses. Because thespherical recess has a greater volume than the polygonal pyramid whichhas the same projected area as the spherical recess, so that the oilpressure of the wedge-shaped oil film increases. In other words, asshown in FIG. 3, the spherical recess allows the flowing oil, whichproduces the oil film when the sliding sections slide with each other,to form a vortex flow with ease in the recess, thereby producing oilpressure which prevents the metal contact.

The spherical shape allows the space between the sliding sections tostay unchanged regardless of the sliding directions, so that the oilfilm can be formed uniformly overall the sliding sections. A deviationof the space between piston 115 and bore 113 thus becomes smaller, andrefrigerant gas 102 leaks in less amount along the side face of piston115.

Further, when recess 123 has a diameter of 20-30 μm and a depth of 1-5μm, the friction coefficient becomes minimum. If this dimension issomewhat enlarged to a diameter of 20-50 μm and a depth of 1-10 μm, thefriction coefficient is still lower than that in the case of manganesephosphate process, and the better sliding condition can be expected.

As the atmospheric pressure lowers, the amount of refrigerant 102dissolving into oil 103 decreases. Comparing with a recess of 50 μmacross and a depth of greater than 10 μm, the recess having a diameterof 20 μm-50 μm and having a depth of 1-10 μm, i.e. having a smallervolume, invites less decrease of the atmospheric pressure. The pressureof compressed refrigerant gas 102 is thus kept at a high level, so thatthe amount of decrease of refrigerant solvable into oil 103 can besuppressed. This mechanism reduces foaming phenomenon of the refrigerantin oil 103. Because this foaming phenomenon breaks the oil film formedon the sliding sections and the breakage invites the metal contact, thereduction of foaming thus prevents the metal contact. The rise offriction coefficient is thus prevented.

The volumes of abrasive wear shown in FIG. 7 also tell the prevention ofthe friction coefficient from rising. The abrasion volumes are measuredin the following conditions:

-   -   atmospheric pressure in CH₂FCF₃ refrigerant; 0.4 MPa,    -   ester oil viscosity; VG8-VG10,    -   sliding speed; 1.0 m/sec, and    -   contact pressure ; 0.5 MPa.

FIG. 7 shows relations between the abrasion volume vs. ratio of the areaof a flat area, other than recesses 123 in the surface area of thesliding section. In other words, as the flat area ratio becomes smaller,recesses 123 account for greater area.

This result proves that the formation of recesses 123 on the surface ofsliding sections produces an abrasion amount less than the surfacethereof undergone the manganese phosphate process. In the case of a flatarea ratio accounting for 52%, an abrasion amount becomes 0 mm³.However, increment of the ratio of the recesses on the sliding surfacearea increases the abrasion amount. Further study in detail of thismatter finds the following result: in the case of a flat area ratioranging from 20% to 60%, in other words, the recessed area ratio vs. thesurface area of the moving parts ranging from 40% to 80%, the abrasionamount falls within less than 0.05 mm³, shown in FIG. 7 with a dottedline, this abrasive amount does not cause any problem in actual use.

Within such a range, it is thought that a slanting surface section and aflat face section are formed on the sliding section. Recesses 123 formwedge-shaped oil film on the slanting surface section in the slidingdirection, and the flat face section is formed in parallel with thesliding face. It is thought that those formations produce a shape andeffect similar to those of the taper land bearing, so that the criticalload supportable by the oil pressure generated increases. As a result,the metal contacts are reduced.

In the case of using iron-based material in the sliding section, steelballs or ceramic balls crash to the surface at a speed greater than agiven speed for forming recesses 123 on the surface of the slidingsection. This method makes the surface layer of the sliding sectionmartensitic, so that the surface strength increases, and the abrasionprogress becomes slower. And the area between sliding sections decreasesdue to forming recesses 123, so that the metal contacts are reduced.

In this embodiment, as discussed above, recesses 123 are provided almostuniformly on the sliding face of piston 115. Recesses 123 can beprovided on bore 113 or both of piston 115 and bore 113 with a similaradvantage.

Next, the sliding section formed by main shaft 109 and bearing 114 isdescribed. FIG. 8 shows an enlarged view of the sliding section formedby main shaft 109 and bearing 114.

Main shaft 109 of crankshaft 108 has recesses 123 on its sliding face125 almost uniformly.

An operation of compressor 100 structured above is demonstratedhereinafter.

Main shaft 109 of crankshaft 108 having recesses 123 on its sliding face125 rotates in bearing 114, then lubricating pump 111 supplies oil 103,which includes the refrigerant, to a sliding section between bearing 114and crankshaft 108. On the other hand, while crankshaft 108 rotates inbearing 114 one turn, the space between main shaft 109 and bearing 114changes in response to a depth of recesses 123. At this time, oil 103 isdrawn into the space between main shaft 109 and bearing 114, therebyforming wedge-shaped oil film.

Since recesses 123 are minutely formed, when oil 103 in which therefrigerant is solved is supplied to recesses 123, the volume changes inrecess 123 only a little and the atmospheric pressure lowers a little.Thus the pressure of compressed refrigerant gas 102 can be kept at ahigh level, so that decrease of a solvable amount of the refrigerant inoil 103 can be suppressed. The foaming phenomenon of the refrigerant inoil 103 is thus suppressed. Because this foaming phenomenon breaks theoil film formed on the sliding sections and the breakage invites themetal contact, the suppression of the foaming phenomenon thus preventsthe metal contact, and the rise of friction coefficient is prevented.

At the operation start of compressor 100, the sliding sections are notyet lubricated; however, since oil 103 is pooled in recesses 123, oil103 always exists between bearing 114 and main shaft 109. As a result,the locked load rises and abnormal abrasion is prevented.

As discussed above, in this embodiment, main shaft 109 of crankshaft 108has recesses 123 almost uniformly formed on its sliding section. Theformation of recesses 123 reduces the slid area, so that the metalcontacts are reduced. Recesses 123 can be provided to bearing 114, or toboth of main shaft 109 and bearing 114 with a similar advantage.

Next, the sliding section formed by connecting rod 118 and piston-pin117 is described. FIG. 9 shows an enlarged view of a vicinity of thepiston shown in FIG. 1. FIG. 10 shows an enlarged view of the slidingsection formed by piston-pin 117 and connecting rod 118.

Piston-pin 117 has recesses 123 almost uniformly on its sliding face127. The formation of recesses 123 reduces the slid area of the slidingsection, so that the metal contacts are reduced.

An operation of compressor 100 structured above is demonstratedhereinafter. Rotary motion of crankshaft 108 is transferred viapiston-pin 117 coupled to connecting rod 118, thereby reciprocatingpiston 115 in bore 113. At this time, rod 118 and piston-pin 117 performrocking motion, and when piston 115 reaches its upper dead center orbottom dead center, the speed of the rocking motion becomes 0 m/sec(zero), and the oil film cannot be formed. At this time, oil 103 isretained each one of recesses 123 formed on sliding face 127 ofpiston-pin 117, so that oil 103 always exists between the slidingsections. As a result, the locked load rises and abnormal abrasion isprevented.

As discussed above, in this embodiment, piston-pin 117 has recesses 123almost uniformly on its sliding face 127. Recesses 123 can be formed onconnecting rod 118, or both on pin 117 and rod 118 with a similaradvantage.

Next, the sliding section formed on thrust bearing 135 is described.FIG. 11 shows an enlarged view of the vicinity of thrust bearing 135shown in FIG. 1. FIG. 12 shows an enlarged view of the contact sectionbetween thrust section 130 and thrust washer 134.

Thrust section 130 has recesses 123 almost uniformly on its sliding face130A.

An operation of compressor 100 structured above is demonstratedhereinafter.

Rotor 105 is press-fitted to crankshaft 108 and has flange face 132, andthe upper end of bearing 114 forms thrust section 130. Thrust washer 134is inserted between flange face 132 and thrust section 130, so thatflange face 132, thrust section 130 and thrust washer 134 form thrustbearing 135, which bears vertical load of crankshaft 108 and rotor 105and so on. While compressor 100 is halted, thrust bearing 135 receivesthe vertical load.

Formation of recesses 123 on sliding face 130A of thrust section 130allows recesses 123 to retain oil 103 even at the start of operation ofcompressor 100, namely, lubrication is not carried out yet at the start.This oil retention lowers the friction coefficient of the slidingsection and reduces the sliding loss when metal contacts occur betweenthrust section 130 and thrust washer 134. Further, since recesses 123retain oil 103, the sliding section always has oil 103, so that thelocked load rises to prevent abnormal abrasion. The formation ofrecesses 123 reduces the slid area between the sliding sections, so thatthe metal contacts are also reduced.

As discussed above, in this embodiment, thrust bearing 135 is formed offlange face 132, thrust section 130 and thrust washer 134, and recesses123 are formed on sliding face 130A. Flange face 136 working as thrustsection 137 also exists between main shaft 109 and eccentric section 110of crankshaft 108. Flange face 136 and thrust section 139, whichconfronts flange face 136, of bearing 114 can form a thrust bearing. Inthis case, recesses 123 are provided to thrust section 137 to obtain asimilar advantage.

In this embodiment, recesses 123 are provided almost uniformly onsliding face 130A of thrust section 130 of bearing 114; however, theycan be provided to thrust washer 134, or to both of washer 134 andthrust section 130 with a similar advantage. Recesses 123 can be alsoprovided on a face of rotor 105 contacting the flange face. Recesses 123can be provided to thrust section 137 of crankshaft 108, or to both ofthrust section 137 of crankshaft 108 and thrust section 139 of bearing114 with a similar advantage.

Next, the relation between a size of recess 123 and a viscosity of oil103 is described in the case of refrigerant 102 easy-solvable in oil103. FIG. 13 shows the characteristics of friction coefficients betweenthe sliding face, on which fine recesses are formed almost uniformly,and a manganese phosphate layer. FIG. 14 shows the characteristics ofrefrigerating capacity of the compressors of which sliding faces areprovided with fine recesses almost uniformly or with a manganesephosphate layer. FIG. 15 shows the characteristics of efficiency of thecompressors of which sliding faces are provided with fine recessesalmost uniformly or with a manganese phosphate layer.

In FIG. 1, container 101 is filled with refrigerant gas 102 made fromisobutane, and pools oil 103, made from mineral oil and having aviscosity less than VG10 and not less than VG5, at its bottom. Otherstructures remain unchanged as previously discussed.

Movements at respective sliding sections formed by the followingelements are demonstrated hereinafter: main shaft 109 and bearing 114;piston 115 and bore 113; piston-pin 117 and connecting rod 118;eccentric section 110 and connecting rod 118. The case of piston 115 isdemonstrated as an example.

At the respective sliding sections, since oil 103 has a viscosity as lowas less than VG10 and not less than VG5, contacts between solid bodiestend to occur. Further, since the refrigerant is formed of isobutane, ittends to dissolve into oil 103 formed of mineral oil, so that theviscosity of the oil lowers, which invites the solid contacts morefrequently.

However, as shown in FIG. 3, the flow of oil, which generates oil filmin sliding of the sliding sections, produces a vertex flow in sphericalrecess 123 with ease, and thus an oil pressure is generated, whichprevents the solid contacts. As a result, the abrasion resistance isimproved. The formation of recesses 123 reduces slid area of the slidingsections, so that the metal contacts can be reduced.

On top of that, since recesses 123 are formed by crashing steel balls orceramic balls having a high hardness to the sliding faces at a speedhigher than a certain level, the hardness of the surface increasesbecause of work hardening. Therefore, even if the contacts between solidbodies happen, abnormal abrasion can be prevented, which improves theabrasion resistance. In particular, in the case of the sliding sectionformed by piston 115 and bore 113, or piston-pin 117 and connecting rod118, the relative sliding speed becomes 0 m/sec twice per compressingprocess. The oil pressure thus becomes 0 (zero), which tends to invitethe solid contacts. The technique discussed above is thus substantiallyeffective to the foregoing sliding sections.

Friction coefficients in the cases of a sliding face provided with finerecesses 123 uniformly formed and a sliding face provided with manganesephosphate process are described depending on an oil viscosity. Thefriction coefficients are measured in the following condition:

-   -   atmospheric pressure in CH₂FCF₃ refrigerant; 0.4 Mpa,    -   ester oil viscosity; VG4-VG22, and    -   ethanol as an oil having viscosity corresponding to VG1.        First, discs are prepared, on which the following recesses 123        are almost uniformly provided,.

(1) diameter; 2 μm-15 μm, depth; 0.5 μm-1 μm

(2) diameter; 40 μm-50 μm, depth; 7 μm-10 μm

(3) diameter; 60 μm-70 μm, depth; 15 μm-20 μm

Those discs are rotated at a sliding speed of 1.0 m/sec, and aring-shaped counterpart member is pressed to those discs at contactpressure of 0.5 MPa. FIG. 13 shows the result of such an abrasion test.

This result tells that the friction coefficient rises with the oilhaving viscosity less than VG10 in the following two cases: providingmanganese phosphate process, providing recesses 123 of diameter of 60μm-70 μm, depth of 15 μm-20 μm. On the other hand, the frictioncoefficient does not rise in the following two cases even the viscosityof oil is lowered to VG8: providing recesses 123 of diameter of 40 μm-50μm, depth of 7 μm-10 μm, providing recesses 123 of diameter of 2 μm-15μm, depth of 0.5 μm-1 μm. The viscosity is further lowered to VG4 tofind the friction coefficient rise slightly. The result tells also thecoefficient is lower than that of in the case of providing the manganesephosphate process.

In the case of a sliding face having almost uniform recesses 123 ofdiameter of 40 μm-50 μm, depth of 7 μm-10 μm, or recesses 123 ofdiameter of 2 μm-15 μm, depth of 0.5 μm-1 μm, a dynamic pressure betweenthe sliding sections is uniformed, so that the space between the slidingsections becomes constant. Further study in detail of this subject findsthat the recesses having an intermediate size between the foregoing twosizes can produce a similar advantage. Volumetric change in recess 123becomes smaller, so that a pressure at the space between the slidingsections lowers only a little. This pressure is generated when oil 103including refrigerant 102 is supplied to recesses 123. This mechanismsuppresses foaming phenomenon of oil 103, and a breakage in the oil filmis prevented, so that an oil pressure of the oil film increases. Theload applied to the solid contacts can be thus reduced, thereby loweringthe friction coefficient.

FIGS. 14 and 15 show the results of measuring a change in refrigeratingcapacity of a reciprocating compressor and a change in coefficient ofperformance (COP) of the compressor using the oil viscosity as aparameter.

The changes are measured in the following conditions: recesses 123 ofdiameter of 2 μm-50 μm, depth of 0.5 μm-10 μm are uniformly provided tothe sliding section of piston 115; isobutane refrigerant, mineral oilsof VG5 and VG10 are used; condensation temperature is 54.4° C.,evaporation temperature is −23.3° C.; suction gas at a temperature of32.2° C. before an expansion valve. FIGS. 14 and 15 compare the changesmeasured in the cases of providing the manganese phosphate process andproviding recesses 123.

FIG. 14 shows that the refrigerating capacity substantially lowers toapprox. 11 W when the viscosity of oil 103 is lowered from VG10 to VG5in the compressor using a piston undergone the manganese phosphateprocess. On the other hand, compressor 100 using a piston with recesses123 lowers in the refrigerating capacity by as small as only 1 W.

When piston 115 reciprocates in bore 113 and compresses refrigerant gas102, the viscosity of oil 103 is so low that its sealing propertylowers. Refrigerant gas 102 compressed in compressing room 116 thusleaks from the space between piston 115 and bore 113 into container 101,so that the refrigerating capacity tends to lower. However, recesses 123provided to piston 115 form wedge-shaped oil film, which reduces aleaking amount of the refrigerant gas from the space between piston 115and bore 113.

To be more specific, when refrigerant gas 102 leaking from the spacebetween piston 115 and bore 113 reaches recess 123, the volume of thespace between piston 115 and bore 113 increases at recess 123. Thus asimilar operation to a labyrinth seal happens, so that the flow speed ofleaking gas 102 sharply slows down, which reduces a leakage amount ofgas 102. As a result, the decrease in refrigerating capacity of thecompressor is suppressed within a substantially small amount.

In the same manner, FIG. 15 shows that compressor 100 using piston 115with recesses 123 increases its COP more than that of the compressorusing the piston with manganese phosphate process, where the COPindicates an efficiency of a compressor. This is because, as FIG. 14shows, the decrease in refrigerating capacity of compressor 100 issuppressed within a so small amount that the volumetric efficiency iskept unchanged. As shown in FIG. 13, this is also because the rise ofthe friction coefficient is extremely smaller than the piston undergonethe manganese phosphate process, so that the input is reduced. Thedecrease of oil viscosity from VG10 to VG5 lowers the viscousresistance. This fact contributes greatly to the decrease of input tothe compressor.

In the foregoing description, the combination of isobutane and mineraloil is taken as an example. However, use of propane, which is alsohydrocarbon-based refrigerant, as refrigerant 102, or use ofalkylbenzene, ester, polyvinylether, polyalkyleneglycol as oil 103, alsosolves refrigerant 102 into oil 103 to lower the viscosity, and asimilar advantage can be expected in the same structure discussed above.

In the foregoing description, recesses 123 of diameter of 2 μm-50 μm,depth of 0.5 μm-10 μm are almost uniformly provided to both of thesliding sections; however, recesses 123 can be provided to either one ofthe sliding sections with a similar advantage.

In the foregoing description, the case where fine recesses 123 areformed on piston 115 is discussed; however, a similar advantage can beobtained in other sliding sections in the same manner.

The oil viscosity is preferably ranges from less than VG10 to not lessthan VG5. This viscosity allows recess 123 to retain oil 103, so thatoil 103 is always maintained on the sliding face. In sliding, the spacebetween the sliding sections changes minutely, which generates dynamicpressure therebetween, so that the oil film can be maintained with ease,and a frequency of solid contacts is reduced. At the sealed section, thesealing property is improved, so that the reliability and efficiency areimproved.

Exemplary Embodiment 2

FIG. 16 shows a sectional view of compressor 200 in accordance with asecond exemplary embodiment of the present invention. FIG. 17 shows arefrigerating cycle of a refrigerating machine which includes compressor200 shown in FIG. 16. FIG. 18 shows a sectional view taken along line18-18 of FIG. 16. FIG. 19 shows an enlarged view of a section contactingbetween vane 216 and rolling piston (hereinafter referred to simply aspiston) 215 shown in FIG. 18. FIG. 20 shows an enlarged view of asection contacting between piston 215 and eccentric section 207 shown inFIG. 18.

Closed container (hereinafter referred to simply as “container”) 101accommodates motor section 106 formed of stator 104 and rotor 105,rolling-piston compressor section 205 driven by motor section 106, andoil 103. Motor section 106 works as a driver.

Compressor section 205 has shaft 210, cylinder 212, main-bearing 213,sub-bearing 214, piston 215, and plate-like vane 216. Shaft 210 haseccentric section 207, main shaft 208 and sub-shaft 209. Cylinder 212forms compressing room 211. Main bearing 213 and sub-bearing 214 sealboth of the end faces of cylinder 212, and rotatably support main shaft208 and sub-shaft 209 respectively. Piston 215 is loosely fitted ineccentric section 207 and rolls in compressing room 211. Vane 216 ispressed by piston 215, thereby partitioning off compressing room 211into a high pressure side and a low pressure side. Rotor 105 is fixed tomain shaft 208.

Oil pump 217 fixed to sub-bearing 214 communicates with oil 103, andsupplies oil 103 to respective sliding sections formed by the followingelements: eccentric section 207 and piston 215; main shaft 208 and mainbearing 213; sub-shaft 209 and sub-bearing 214. The foregoing elementsthat form the sliding sections are contact sections sliding against eachother due to the driving of compressor section 200.

As shown in FIGS. 19 and 20, fine recesses (hereinafter referred tosimply as recesses) 123 are formed almost uniformly on sliding face 218of piston 215 and sliding face 219 of eccentric section 207. Although itis not shown in the drawings, recesses 123 are formed almost uniformlyon a sliding face of main shaft 208 and a sliding face of sub-shaft 209.Recesses 123 are preferably shaped spherical similar to those in thefirst embodiment, and the size of recess 123 is preferably of diameterof 20 μm-50 μm and depth of 1 μm-10 μm. Further, the recesses preferablyaccount for 40-80% of the surface area of the each sliding face. In thecase of using iron-based material, the surface of the sliding sectionpreferably undergoes martensitic process.

An operation of compressor 200 structured above is demonstratedhereinafter.

The rotation of rotor 105 accompanies the spin of shaft 210, and piston215 loosely fitted in eccentric section 207 rolls in compressing room211. Then respective volumes of the high pressure side and the lowpressure side in compressing room 211 partitioned off by vane 216 changecontinuously. The refrigerant gas is thus continuously compressed. Thecompressed gas is discharged into container 101 and sent to heatexchanger 70 via discharging path 220, then dissipates the heat to theoutside and returns to heat exchanger 60 via expansion valve 80, andcollects heat from the outside. The refrigerating machine thus works.

As discussed above, container 101 has high-pressure atmosphere therein.The high-pressure in container 101 works as back pressure to vane 216,so that the ambient pressure in container 101 urges the tip of vane 216against the outer surface of piston 215. At the section where the tip ofvane 216 is urged against the outer surface of piston 215, the contactis produced by the arc of vane 216 and the arc of piston 215, i.e. linecontact is produced, so that metal contact happens frequently.

Recesses 123 are formed almost uniformly on the outer surface of piston215, so that the sliding area is reduced, and the metal contactdecreases. Recesses 123 retain oil 103, so that the sliding sectionalways maintains oil 103. The locked load is thus increased, andabnormal abrasion can be prevented. Recesses 123 can be formed on vane216 instead of on the outer surface of piston 215, or they can be formedon both of outer surface of piston 215 and vane 216 with a similaradvantage.

The spin of shaft 210 accompanies the supply of oil 103 from oil pump217 to respective sliding sections. Recesses 123 are formed almostuniformly on sliding section 219 of eccentric section 207, slidingsections of main shaft 208 and sub-shaft 209. Oil 103 is thus drawn intothe spaces between respective sliding sections formed by eccentricsection 207 and piston 215, main shaft 208 and main bearing 213, andsub-shaft 209 and sub-bearing 214, so that wedge-shaped oil film isformed there.

In compressor 200 using a rolling piston, piston 215 is loosely androtatably fitted in eccentric section 207. The relative speed of piston215 vs. eccentric section 207 is smaller than those of main shaft 208vs. main bearing 215, and sub-shaft 209 vs. sub-bearing 214. Sommerfeldconstant S, which indicates the characteristics of journal bearing andfound from formula (1), thus becomes smaller, which is disadvantageousto lubricating the sliding sections.S=μ×N/P×(R/C)²  (1)As formula (1) tells, Sommerfeld constant S is found by R: radius of thebearing, C: clearance (space) of between piston 215 and eccentricsection 207 in radius, N: speed, μ: viscosity of the oil, and P: contactpressure.

However, the space changes in response to a depth of recesses 123, sothat the oil is drawn into the space between piston 215 and eccentricsection 207 and the wedge-shaped oil film is formed even if the slidingspeed is slow.

Further in the compressor using the rolling piston, container 101 has acondensation pressure therein, so that the internal pressure is high,and oil 103 dissolves into the refrigerant with ease. The viscosity ofthe oil thus lowers, and Sommerfeld constant S becomes smaller, which isdisadvantageous to lubricating the sliding sections.

However, since recesses 123 are minutely formed, when oil 103 in whichthe refrigerant dissolves is supplied into recesses 123, the volume ofoil 103 changes only a little and the ambient pressure lowers only alittle. In other words, the compressed refrigerant gas keeps itspressure high. Thus a decrease of a solvable amount of refrigerant intothe oil is suppressed, and a foaming phenomenon of the refrigerant inthe oil decreases, so that the foaming phenomenon of refrigerant in theoil is suppressed. Because the foaming phenomenon invites breakage ofthe oil film, the decrease of the foaming will prevent the metalcontact, and prevents the friction coefficient from rising.

Recesses 123 are almost uniformly to the sliding faces of eccentricsection 207, main shaft 208, and sub-bearing 209. Recesses 123 can beprovided to the inner surface of piston 215, main bearing 213, andsub-bearing 214, or to both of eccentric section 207 and the innersurface of piston 215, both of main shaft 208 and main bearing 213, andboth of sub-shaft 209 and sub-bearing 214. Those modifications canobtain a similar advantage to what is discussed previously.

Next, the relation between a size of recess 123 is described in the caseof the combination of refrigerant 102 solvable with ease into oil 103.

In FIG. 16, oil 103 enclosed in container 101 is made from mineral oiland has a viscosity less than VG10 and not less than VG5. Refrigerantgas (not shown) is made from isobutane.

As it is already discussed, eccentric section 207 and piston 215, mainshaft 208 and main bearing 213, sub-shaft 209 and sub-bearing 214,respectively form the sliding sections each other. Recesses 123 areformed almost uniformly on iron-based material which is the basematerial of those sliding sections. The size of recesses 123 is ofdiameter of 2-50 μm, depth of 0.5-10 μm. Recesses 123 are formed bycrashing steel balls or ceramic balls having a high hardness to slidingface 219 of eccentric section 207 at a speed higher than a certainlevel. The surface hardness of sliding face 219 increases because ofwork hardening. This method increases the abrasion resistance, and evenif the contacts between solid bodies happen, abnormal abrasion can beprevented. The foregoing size of recesses 123 reduces the occurrence ofsolid contacts even if the refrigerant is easily solvable into oil 103,thereby preventing the friction coefficient from rising as in the firstexemplary embodiment.

In the foregoing description, a combination of isobutane and mineral oilis taken as an example. However, use of propane, which is alsohydrocarbon-based refrigerant, as refrigerant 102, or use ofalkylbenzene, ester, polyvinylether, polyalkyleneglycol and so on as oil103, also solves the refrigerant into oil 103 to lower the viscosity,and a similar advantage can be expected in the same structure asdiscussed above.

Exemplary Embodiment 3

The compressor in accordance with the present exemplary embodiment hasbasically a similar structure to that shown in FIG. 1 described in thefirst embodiment. The structure here differs from the first one inrespective sliding sections formed by the following elements: main shaft109 and bearing 114; piston 115 and bore 113; piston-pin 117 andconnecting rod 118; eccentric section 110 and connecting rod 118. Theelements forming the sliding sections are contact sections that contactwith each other by driving compressor section 107.

FIGS. 21A, B show enlarged views of the sliding section formed by piston115 and bore 113. In FIG. 21A, mixed layer 323, to which molybdenumdisulfide (MoS₂) is bound, is formed on sliding face 324, which is thesurface of iron-based material, i.e. base material of piston 115. Purityof MoS₂ is preferably not lower than 98%, and as shown in FIG. 21B, finerecesses 123 are preferably formed almost uniformly on sliding face 324.Further the surface of each one of recesses 123 preferably shapes like asphere, and the recess preferably has a diameter of 2-20 μm, and a depthof 0.2-1.0 μm.

A method of forming MoS₂ on sliding face 324 as shown in FIG. 21A isdemonstrated hereinafter. Thermosetting resin such as imido group isused as a binder, and this binder is solved into solvent such asdimethylacetamide, then particles of MoS₂ are put into this solution.Then the resultant solution is applied to sliding face 324, and it isbaked at several hundreds ° C.

Next, a method of forming mixed layer 323 to which MoS₂ is bound asshown in FIG. 21B is demonstrated. Particles of MoS₂ are crashed to thesliding face at a speed greater than a certain level, which face is madefrom metal such as iron-based or aluminum-based material which is basematerial of the sliding section. This method allows parts of MoS₂ todissolve into the base material and form metallic bond due to the heatenergy generated in crashing. This metallic bond allows mixed layer 323to form on the base material, and the impact in crashing forms recesses123.

An operation of compressor 100 structured above is demonstratedhereinafter with reference to FIG. 1, FIGS. 21A and 21B.

Commercial power is supplied to motor section 106, thereby spinningrotor 105 of motor section 106. Rotor 105 rotates crankshaft 108, andeccentric movement of eccentric section 110 drives piston 115 viaconnecting rod 118 of the coupling section and piston-pin 117. Piston115 thus reciprocates in bore 113. Refrigerant gas 102 guided throughsuction tube 121 into container 101 is sucked from suction muffler 122and compressed continuously in compressing room 116.

In this case, when piston 115 reaches its top dead center or bottom deadcenter, the speed becomes 0 m/sec, and metal contacts happen frequently.However, the formation of mixed layer 323, to which MoS₂ is bound, onthe surface of piston 115 allows MoS₂ to exert its self lubricatingfunction, so that the friction coefficient lowers and the abrasion lossdecreases.

According to the structure shown in FIG. 21B, recesses 123 are formedalmost uniformly on mixed layer 323 of sliding face 324 of piston 115.This structure allows producing a similar advantage to that of the firstembodiment. To be more specific, the formation of recesses 123 reducesthe slid area between the sliding sections, so that the metal contactsare reduced. When leakage gas from the space between piston 115 and bore113 reaches recesses 123 on piston 115, the volume of the space betweenpiston 115 and bore 113 increases at each one of recesses 123. Thus asimilar operation to a labyrinth seal happens, so that the flow speed ofthe leakage gas sharply slows down, which reduces a leakage amount ofthe gas. As a result, the volumetric efficiency of the compressorincreases, so that the compression efficiency increases.

FIG. 22 shows a flow of the oil in sliding of this embodiment. Thespherical shape of recess 123 allows the flow of oil 103, which producesoil film at the sliding, to form a vertex flow with ease in therecesses. The vertex flow contributes to generating oil pressure, whichprevents the metal contacts, so that the abrasion resistance increases.The spherical shape allows the space between the sliding sections tostay unchanged regardless of a sliding direction, so that the oil filmcan be formed uniformly overall the sliding sections. A deviation of thespace between piston 115 and bore 113 becomes smaller, and thusrefrigerant gas 102 leaks in less amount along the side face of piston115.

Next, results of measurement of friction coefficients are describedreferring to FIG. 23 of the characteristics of the friction coefficient.Friction coefficients are measured in the following cases:

a sliding face provided with mixed layer 323 in which MoS₂ is bound tothe iron-based material, and a sliding face without mixed layer;

a sliding face further provided with fine recesses 123 uniformly formed,and a sliding face provided without recesses 123;

The friction coefficients are measured in the following condition:

-   -   atmospheric pressure in CH₂FCF₃ refrigerant; 0.4 MPa,    -   ester oil viscosity; VG8-VG10,    -   sliding speed; 1.0 m/sec, and    -   contact pressure; 0.5 MPa.

The result tells that the presence of mixed layer 323, in which MoS₂ isbound to the iron-based material, lowers the friction coefficientcomparing with the case of using the sliding face undergone themanganese phosphate process. The structure of MoS₂, which forms mixedlayer 323, is dense hexagonal system, and the size of its molecule is assmall as approx. 6×10⁻⁴ μm. Therefore, when this structure touches thecounterpart such as iron-based material or aluminum-based material, thestructure is cleaved at a low friction coefficient, so that the frictioncoefficient at the sliding sections, where the metal contact happens, islowered. The friction coefficient of the impurities such aspolyamide-imidic resin (PAI) used as binder is higher than that of MoS₂,so that the purity of MoS₂ is preferably set at not lower than 98%.

The formation of spherical recesses 123, having a diameter of 2-20 μmand a depth of 0.2-1.0 μm, on mixed layer 323, in which MoS₂ is bound toiron-based material, further lowers the friction coefficient. Becausethe formation of recesses 123 increases the oil pressure of thewedge-shaped oil film, the load applied to the metal contacting sectionis reduced, and the friction coefficient lowers.

An amount of abrasive wear is measured when spherical recesses 123having a diameter of 2-20 μm and a depth of 0.2-1.0 μm are formed onmixed layer 323 in which MoS₂ is bound to the iron-based material. FIG.24 shows the characteristics of the amount of abrasive wear in thefollowing two cases: a sliding face provided with mixed layer 323 onwhich recesses 123 are formed almost uniformly; a sliding face withoutmixed layer and undergone manganese phosphate process. The amounts aremeasured in the following conditions:

-   -   atmospheric pressure in CH₂FCF₃ refrigerant; 0.4 MPa,    -   ester oil viscosity; VG8-VG10;    -   sliding speed; 1.0 m/sec, and    -   contact pressure; 0.5 MPa    -   time of test; 20 hours        The result tells that mixed layer with recesses 123 produces        less amount of abrasive wear than manganese phosphate process        does. Because the formation of recesses 123 reduces the slid        area between the sliding sections, the metal contacts are        reduced. The oil pressure of the wedge-shaped oil film is        increased, so that the load applied to the metal contacting        section is lowered. Further, the method of crashing the        particles of MoS₂ to the surface of iron-based material forms        mixed layer 323, to which MoS₂ is bound, and recesses 123        simultaneously. Thus MoS₂ enters into the base material and        parts of MoS₂ form intermetallic compound, thereby further        increasing the abrasion resistance.

In this embodiment, mixed layer 323 to which MoS₂ is bound is providedto sliding face 324 of piston 115, and on top of that, recesses 123having a diameter of 2-20 μm and a depth of 0.2-1.0 μm are formed almostuniformly. Such mixed layer 323 can be provided to bore 113, or to bothof piston 115 and bore 113 with a similar advantage.

Next, the sliding section formed by main shaft 109 and bearing 114 isdescribed. FIGS. 25A, B show enlarged views of the sliding sectionformed by main shaft 109 and bearing 114.

Main shaft 109 of crankshaft 108 is made from mainly iron-basedmaterial, and MoS₂ is input in this base material, so that mixed layer323, in which MoS₂ is bound to metal material, is formed. Morepreferable state of mixed layer 323 is previously discussed. FIG. 25Bshows the case where recesses 123 are formed on sliding face 328, i.e.the surface of mixed layer 323.

The formation of mixed layer 323 lowers the friction coefficient of thesliding section, so that even if metal contacts happen between bearing114 and crankshaft 108 when the compressor starts operating, losses dueto the sliding can be reduced. Meanwhile at the operation start, nolubrication is done to the sliding sections yet.

On top of that, the formation of recesses 123 almost uniformly on mixedlayer 323 obtains a similar advantage to that of the first embodiment.

In this embodiment, mixed layer 323, to which MoS₂ is bound, is providedto main shaft 109. Further, recesses 123 having a diameter of 2-20 μmand a depth of 0.2-1.0 μm are formed almost uniformly on mixed layer323. Mixed layer 323 can be provided to bearing 114, or to both of mainshaft 109 and bearing 114 with a similar advantage.

Next, the sliding section formed by connecting rod 118 and piston-pin117 is described hereinafter. FIGS. 26A, B show enlarged views of thesliding section formed by connecting rod 118 and piston-pin 117.

Mixed layer 323, to which MoS₂ is bound, is formed on sliding face 331of piston-pin 117. More preferable state of mixed layer 323 ispreviously discussed. FIG. 26B shows the case where recesses 123 areformed almost uniformly on the surface of mixed layer 323.

Connecting rod 118 and piston-pin 117 move at speed 0 m/sec when piston115 reaches its top dead center or bottom dead center, and the oil filmcannot be formed, so that metal contacts happen. In such a case, theformation of mixed layer 323 lowers the friction coefficient of thesliding sections, and the loss due to the sliding can be reduced.

On top of that, the formation of recesses 123 almost uniformly on mixedlayer 323 obtains a similar advantage to that of the first embodiment.

In this embodiment, mixed layer 323, to which MoS₂ is bound, is providedto sliding face 331 of piston 117. Further, recesses 123 having adiameter of 2-20 μm and a depth of 0.2-1.0 μm are formed almostuniformly on mixed layer 323. Mixed layer 323 can be provided toconnecting rod 118, or to both of piston-pin 117 and connecting rod 118with a similar advantage.

Next, the sliding section formed at thrust bearing 135 is described.FIGS. 27A, B show enlarged views of a section where thrust section 130contacts thrust washer 134.

Mixed layer 323, to which MoS₂ is bound, is formed on sliding face 335of thrust section 130. More preferable state of mixed layer 323 ispreviously discussed. FIG. 27B shows the case where recesses 123 areformed almost uniformly on the surface of mixed layer 323. Morepreferably state of recesses 123 is previously discussed.

While the compressor is halted, vertical load is applied to thrustbearing 135, and yet, the lubrication is not done yet to the slidingsections and metal contacts happen between thrust section 130 and thrustwasher 134 at starting the operation of the compressor. Even in such acase, the formation of mixed layer 323 will lower the frictioncoefficient, so that the loss due to the sliding can be reduced.

On top of that, the formation of recesses 123 almost uniformly on mixedlayer 323 obtains a similar advantage to that of the first embodiment.

In this embodiment, mixed layer 323, to which MoS₂ is bound, is providedto sliding face 335 of thrust section 130 of bearing 114. Further,recesses 123 having a diameter of 2-20 μm and a depth of 0.2-1.0 μm areformed almost uniformly on the surface of mixed layer 323. Mixed layer323 can be provided to thrust washer 134, or to both of thrust section130 and thrust washer 134 with a similar advantage.

In this embodiment, thrust bearing 135 is formed by flange-face 132,thrust section 130, and thrust washer 134. Mixed layer 323 is formed onsliding face 335. Flange face 136 also exists between main shaft 109 ofcrankshaft 108 and eccentric section 110. The thrust bearing can beformed by flange face 136 and thrust section 139, which confronts flangeface 136, of bearing 114. In this case, mixed layer 323 is provided tothrust section 137. In the case of forming the thrust bearing asdiscussed above, a similar advantage to what is discussed previously isobtainable.

Mixed layer 323 can be provided to thrust washer 134, or to both ofthrust washer 134 and thrust section 130 with a similar advantage. Mixedlayer 323 also can be provided to thrust washer 134 at its facecontacting the flange face of rotor 105. Mixed layer 323 can be providedto flange face of rotor 105. Mixed layer 323 can be provided to thrustsection 137 of crankshaft 108, or to both of thrust section 137 ofcrankshaft 108 and thrust section 139 of bearing 114 with a similaradvantage.

Use of isobutane or propane, which are hydrocarbon-based refrigerant, asrefrigerant 102, or use of mineral oil, alkylbenzene, ester,polyvinylether, polyalkyleneglycol as oil 103, also solves refrigerant102 into oil 103 to lower the viscosity, and a similar advantage can beexpected in the same structure as discussed above. This is detailedbelow.

FIG. 28 shows the characteristics of friction coefficients in thefollowing two cases: one case where fine recesses 123 are formed onmixed layer 323 to which MoO₂ is bound; the other case where a manganesephosphate layer is formed. FIG. 29 shows the characteristics ofrefrigerating capacity of two compressors including the piston and borehaving the structures discussed above, namely, one compressor with mixedlayer 323, and the other compressor with the manganese phosphate layer.FIG. 30 shows the coefficients of efficiency of the foregoing twocompressors.

In FIG. 1, container 101 is filled with refrigerant gas 102 made fromisobutane, and pools oil 103, made from mineral oil and having aviscosity less than VG10 and not less than VG1, at its bottom. Container101 accommodates motor section 106 having stator 104 and rotor 105 aswell as reciprocating compressor section 107 driven by motor section106.

Sliding sections are formed by the following elements: main shaft 109and bearing 114; piston 115 and bore 113; piston-pin 117 and connectingrod 118; eccentric section 110 and connecting rod 118. Those slidingsections are the contact sections that contact with each other bydriving compressor section 107.

On the surface of the foregoing sliding sections of which base materialis iron-based material, mixed layer 323 to which MoS₂ is bound isformed. On top of that, recesses 123 having a diameter of 2-50 μm and adepth of 0.5-10 μm are formed almost uniformly

At the respective sliding sections, since oil 103 has a viscosity as lowas less than VG10 and not less than VG1, solid contacts between thesliding components tend to occur. Further, since the refrigerant isformed of isobutane, it tends to dissolve into oil 103, so that theviscosity of oil 103 lowers, which invites the solid contacts morefrequently. In the case of the sliding sections formed by piston 115 andbore 113, or by piston-pin 117 and connecting rod 118, the relativesliding speed becomes 0 m/sec twice per compressing process. The oilpressure thus becomes 0 (zero), which invites the solid contacts.

However, since piston 115 has mixed layer 323, to which MoS₂ is bound,on its surface layer, the solid lubricating function of MoS₂ works, sothat abnormal abrasion is prevented, and the friction coefficient lowersand the loss due to the sliding can be reduced.

Further, as shown in FIG. 22, the flow of oil, which generates oil filmin sliding, produces a vertex flow in recess 123 with ease, and thus anoil pressure is generated, which prevents the solid contacts andimproves the abrasion resistance.

A friction coefficient in response to the changes of viscosity of oil103 is described with reference to FIG. 28. The friction coefficient ismeasured in the following conditions:

-   -   atmospheric pressure in CH₂FCF₃ refrigerant; 0.4 MPa,    -   ester oil viscosity; VG4-VG22,    -   ethanol as an oil having a viscosity corresponding to VG1,    -   sliding speed; 1.0 m/sec, and    -   contact pressure ; 0.5 MPa.

The result tells that the sliding section with only the manganesephosphate process increases its friction coefficient at the oilviscosity less than VG10. On the other hand, the sliding section withmixed layer 323 having recesses 123 shows no increase in the frictioncoefficient at the oil viscosity lowered to as low as VG1, which islower than the case of the manganese phosphate process.

FIGS. 29 and 30 show the results of measuring a change in refrigeratingcapacity of a reciprocating compressor and a change in coefficient ofperformance (COP) of the compressor using the oil viscosity as aparameter. Piston 115 made from iron-based material has mixed layer 323,to which MoS₂ is bound, on its sliding face, and mixed layer hasrecesses 123 of diameter of 2 μm-50 82 m, depth of 0.5 μm-10 μmuniformly formed. The changes are measured in the following conditions:isobutane refrigerant and mineral oils of VG5 and VG10 are used;condensation temperature is 54.4° C., evaporation temperature is −23.3°C.; suction gas has a temperature of 32.2° C. before an expansion valve.

In FIG. 29, the compressor having a piston undergone the manganesephosphate process shows a substantial decrease in refrigerating capacitywhen the viscosity of oil 103 is lowered from VG10 to VG5. On the otherhand, the compressor having a piston with mixed layer 323 shows only alittle reduction in the refrigerating capacity.

This fact is seemed to be caused by the effects of recesses 123 as thefirst embodiment already proves, and mixed layer 323.

In FIG. 30, the compressor having a piston with mixed layer 323 to whichrecesses 123 are provided, shows a rise of COP, indicating an efficiencyof the compressor, while the compressor having a piston undergone themanganese phosphate process shows a decline of COP. Because the decreasein the refrigerating capacity of the compressor is suppressed at anextremely low level as shown in FIG. 29, so that the volumetricefficiency is maintained. As shown in FIG. 28, the rise of the frictioncoefficient is extremely smaller than the case of manganese phosphateprocess, the input can be reduced. A lowering in viscous resistance dueto the reduction in oil viscosity from VG10 to VG5 substantiallycontributes to the reduction in the input to the compressor.

In the foregoing description, the combination of isobutane and mineraloil is taken as an example. However, use of propane, which is alsohydrocarbon-based refrigerant, as refrigerant 102, or use ofalkylbenzene, ester, polyvinylether, polyalkyleneglycol as oil 103, alsosolves refrigerant 102 into oil 103 to lower the viscosity, and asimilar advantage can be expected in the same structure discussed above.

In the foregoing description, mixed layer 323 is prepared to both of thesliding sections contacting each other; however, mixed layer 323 can beprovided to either one of the sliding sections with a similar advantage.

In the foregoing description, the case of preparing mixed layer 323 onpiston 115 is demonstrated; however, other sliding sections can obtain asimilar advantage in the same manner.

The viscosity of oil 103 ranges from less than VG10 to not less thanVG1, and if the sliding section retains less amount of oil 103, thesolid lubrication function proper to MoS₂ in mixed layer 323 formed onthe sliding face works to lower the friction coefficient. The loss dueto the sliding is thus reduced, and use of oil 103 of low viscosity alsoreduces the sliding loss.

Exemplary Embodiment 4

The compressor in accordance with a fourth exemplary embodiment hasbasically a similar structure to that shown in FIG. 16 described in thesecond embodiment. This compressor differs from that of the secondembodiment in the sliding sections formed by the following elements:eccentric section 207 and rolling piston (hereinafter referred to simplyas piston) 215; main shaft 208 and main bearing 213; sub-shaft 209 andsub-bearing 214. The foregoing elements forming the sliding sections arecontact sections that contact with each other by driving compressorsection 205.

FIGS. 31A, B show enlarged views of the sliding section formed by piston215 and vane 216. FIGS. 32A, B shows enlarged views of the slidingsection formed by piston 215 and eccentric section 207.

On sliding face 419 of piston 215, mixed layer 323 to which molybdenumdisulfide (MoS₂) is bound is formed. Mixed layer 323 is also formed onsliding face 419 of eccentric section 207 and the surfaces of slidingsections of main shaft 208 and sub-shaft 209. The purity of MoS₂ is setpreferably not lower than 98%, and fine recesses 123 are preferablyformed almost uniformly on the sliding faces as shown in FIGS. 31B, 32B.Further, each one of recesses 123 preferably has spherical surface and adiameter of 2-20 μm and a depth of 0.2-1.0 μm.

An operation of compressor 200 structured above is demonstratedhereinafter with reference to FIG. 16, FIGS. 31A, B and FIGS. 32A, B.

Motor section 106, namely, the driver, is powered, which accompanies therotation of rotor 105, then accompanies the spin of shaft 210, thenpiston 215 loosely fitted in eccentric section 207 rolls in compressingroom 211. Then respective volumes of the high pressure side and the lowpressure side in compressing room 211 partitioned off by vane 216 changecontinuously. The refrigerant gas is thus continuously compressed. Thecompressed gas is discharged into closed container (hereinafter referredto simply as “container”) 101, and makes container 101 high pressureatmosphere. The high-pressure in container 101 works as back pressure tovane 216, so that the ambient pressure in container 101 urges the tip ofvane 216 against the outer surface of piston 215. At the section wherethe tip of vane 216 is urged against the outer surface of piston 215,the contact is produced by the arc of vane 216 and the arc of piston215, i.e. line contact is produced, so that metal contact happensfrequently.

In this case, the formation of mixed layer 323 including MoS₂ on theouter surface of piston 215 lowers the friction coefficient of thesliding section, so that the loss due to sliding is reduced. In thisembodiment, mixed layer 323 is prepared on the outer surface of piston215; however, it can be prepared on vane 216, or on both of the outersurface of piston 215 and piston 215 with a similar advantage.

The spin of shaft 210 prompts oil pump 217 to lubricate oil 103 torespective sliding sections continuously.

Recesses 123 are formed almost uniformly on mixed layers 323 of thesliding surfaces of eccentric section 207, main shaft 208 and sub-shaft209. This structure allows producing a similar advantage to thatproduced in the second embodiment.

As described in the second embodiment, piston 215 is loosely androtatably fitted in eccentric section 207 in the compressor using arolling piston. The relative speed of piston 215 vs. eccentric section207 is smaller than that of main shaft 208 vs. main bearing 215, andthat of sub-shaft 209 vs. sub-bearing 214. This status isdisadvantageous because metal contacts tend to happen in lubricating thesliding sections. However, mixed layer 323 to which MoS₂ is bound isformed on sliding face 419 of eccentric section 207. When the metalcontact happens, since the structure of MoS₂ is dense hexagonal system,and the size of its molecule is as small as approx. 6×10⁻⁴ μm, thestructure is cleaved at a low friction coefficient, so that the frictioncoefficient at the sliding sections, where the metal contact happens, islowered. As a result, the sliding loss is reduced.

In the compressor using the rolling piston, container 101 has acondensation pressure therein, so that the internal pressure is high,and oil 103 dissolves into the refrigerant with ease. The viscosity ofoil 103 thus lowers, which is also disadvantageous in lubricating thesliding sections; however, since recesses 123 are formed on the surfaceof mixed layer 323, a similar advantage to that is produced in thesecond embodiment can be expected.

Mixed layer 323, to which MoS₂ is bound, having fine recesses 123 of2-20 μm across and 0.2-1.0 μm deep, is formed on the sliding faces ofeccentric section 207, main shaft 208, sub-shaft 209. Mixed layer 323can be provided to the inner surface of piston 215, main bearing 213 andsub-bearing 214, or to both of eccentric section 207 and the innersurface of piston 215, main shaft 208 and main bearing 213, sub-shaft209 and sub-bearing 214. Either structure can produce a similaradvantage to what is discussed previously.

Use of isobutane or propane, which is hydrocarbon-based refrigerant, asrefrigerant 102, or use of alkylbenzene, ester, polyvinylether,polyalkyleneglycol as oil 103, solves refrigerant 102 into oil 103 tolower the viscosity, so that the abrasion resistance decreases, and asimilar advantage can be expected in the same structure as discussedabove. This phenomenon is detailed below.

In FIG. 16, oil 103 enclosed in container 101 is made from mineral oiland has a viscosity less than VG10 and not less than VG5. Refrigerantgas (not shown) is made from isobutane.

As it is already discussed, eccentric section 207 and piston 215, mainshaft 208 and main bearing 213, and sub-shaft 209 and sub-bearing 214,form the sliding sections respectively. Mixed layer 323 to which MoO₂ isbound is formed on the surface of iron-based material, which is the basematerial of the sliding sections. This structure allows the MoO₂ tocleave at a low friction coefficient even solid contacts happen, asdemonstrated in the third embodiment. Thus the friction coefficients atthe sliding sections lower, and the sliding loss is reduced. On topthat, recesses 123 are formed almost uniformly on mixed layer 323. Thesize of each one of recesses 123 is of diameter of 2-50 μm, depth of0.5-10 m, and this size can reduce the frequency of solid contacts, andprevent the friction coefficient from rising, even if the refrigerant issolvable with ease in oil 103, as demonstrated in the second embodiment.

In the foregoing description, a combination of isobutane and mineral oilis taken as an example. However, use of propane, which is alsohydrocarbon-based refrigerant, as refrigerant 102, or use ofalkylbenzene, ester, polyvinylether, polyalkyleneglycol as oil 103, alsosolves the refrigerant into oil 103 to lower the viscosity, and asimilar advantage can be expected in the same structure as discussedabove.

In the embodiments 1-4 discussed previously, compressors working at aconstant speed are described. In a climate of using inverter technology,a compressor working at the lower speed has been developed. In the caseof driving the compressor at an ultra slow speed such as slower than 20Hz or starting the compressor at such a slow speed, the compressorencounters abnormal abrasion more often. The present invention exertsits advantage more explicitly in such compressors.

On the other hand, a compressor employing a synchronous induction motor,which works as an induction motor at the start then operatessynchronizing with the power supply frequency, produces strongaccelerating force when it enters to a synchronous operation at thestart. Thus such a compressor encounters abnormal abrasion more often.The present invention exerts its advantage more explicitly in suchcompressors.

According to the principle of the formation of oil film, use ofmaterials other than iron-based one, for example aluminum-based one, asthe sliding sections will also produce a similar advantage to what isdiscussed previously.

Exemplary Embodiment 5

The compressor in accordance with the present exemplary embodiment hasbasically a similar structure to that shown in FIG. 1 described in thefirst embodiment. This compressor differs from that of the firstembodiment in suction valve device 527 provided to valve plate 119 anddischarging valve device 534.

First, the suction valve device is demonstrated. FIG. 33 shows avertical sectional view of the suction valve device in accordance withthis embodiment. FIG. 34 shows a plan view illustrating suction valveport (hereinafter referred to simply as “port”) 517. FIG. 35 shows aplan view illustrating suction movable valve (hereinafter referred tosimply as “valve”) 519 of suction valve device 527.

Valve plate 119 includes port 517, and forms suction valve device 527together with valve 519. Fine recesses 123A are formed almost uniformlyon the mutual sealing faces of port 517 and sealing section 519A ofvalve 519. Port 517 and sealing section 519A of valve 519 are contactsections which are brought into contact with each other by drivingcompressor 107. Fine recesses 123B are formed on arm 519B of valve 519.Recesses 123A, 123B preferably shape in spherical and have a diameter of2-20 μm, a depth of 0.2-1.0 μm. The recesses 123A, 123B preferablyaccount for 40-80% of the surface area of respective mutual sealingfaces.

A method of forming recesses 123A on port 517 and valve 519 is similarto the method of forming recesses 123 demonstrated in the firstembodiment. In the case of using a leaf spring having martensiticsurface structure as port 519, the method similar to the one in thefirst embodiment can be used.

An operation of the compressor structured above is demonstratedhereinafter with reference to FIG. 1 and FIGS. 33-35.

Commercial power is supplied to motor section 106 as a driver, therebyspinning rotor 105 of motor section 106. Rotor 105 rotates crankshaft108, and. eccentric movement of eccentric section 110 drives piston 115via connecting rod 118 of the coupling section and piston-pin 117.Piston 115 thus reciprocates in bore 113. Refrigerant gas 102 guidedthrough suction tube 121 into closed container (hereinafter referred tosimply as “container”) 101 is sucked from suction muffler 122 viasuction valve device 527 and compressed continuously in compressing room116.

Refrigerant gas 102 sucked from suction valve device 527 includes asmall amount of oil 103 in misting state, so that gas 102 supplies oil103 to the mutual sealing faces of port 517 and valve 519 that formsuction valve device 527. Oil 103 supplied works as sealing andlubricating the mutual sealing faces.

When recesses 123A are formed, the surface structure of port 517 andvalve 519 are undergone martensitic process, so that the surfacestrength is increased. Thus the abrasion resistance and impactresistance are increased. The formation of recesses 123A reduces thearea between the contact sections, so that metal contacts are reduced.

Piston 115 reciprocates in bore 113 and compresses refrigerant gas 102.At this time, parts of compressed gas 102 leak from the sealing face ofvalve device 527 to suction muffler 122. This leakage lowers thevolumetric efficiency. However, according to this embodiment, recesses123A are formed almost uniformly on seat 517 and sealing section 519A ofvalve 519 that form suction valve device 527, and oil 103 remains there,which resists compressed refrigerant gas 102 leaking. The sphericalshape of recess 123A increases the volume comparing with a polygonalpyramid having the same area projected to the surface, so that an amountof oil 103 remaining increases. As a result, an amount of leakage of gas102 decreases, and the volumetric efficiency of the compressorincreases, so that the compression efficiency of the compressorincreases.

Oil 103 remaining in recesses 123A contributes to increasing thelubrication on the mutual sealing faces of seat 517 and valve 519, sothat the abrasion resistance of suction valve device 527 increases. Oil103 remaining in recesses 123A damps an impact when valve 519 is seatedon port 517, so that it lowers the noises of the compressor caused bythe impact due to the seating in valve device 527. When recesses 123Bare formed on arm 519B, residual stress of compression is applied tomake the surface martensitic, so that the surface hardness increases andthe impact resistance also increases. As a result, the strength againstfatigue fracture increases.

In this embodiment, recesses 123A are provided to both of port 517 andsealing section 519A of valve 519; however, recesses 123A can beprovided to either one. Recesses 123B are provided to both faces of arm519B of valve 519; however, they can be provided to either one face.

Next, the discharging valve device is demonstrated. FIG. 36 shows avertical sectional view of discharging valve device 534 in accordancewith the fifth embodiment. FIG. 37 shows a plan view illustratingdischarging valve port (port) 528 of discharging valve device 534. FIG.38 shows a plan view illustrating a mutual sealing face of dischargingmovable valve (valve) 525 of discharging valve device 534. FIG. 39 showsa plan view illustrating striking section 541A side of valve 525 ofdischarging valve device 534. FIG. 40 shows a plan view illustratingstopper 537 of discharging valve device 534.

Valve plate 119 includes port 528, and forms discharging valve device534 together with valve 525 and stopper 537. Port 528 and sealingsection 525A of valve 525 are contact sections which are brought intocontact with each other by driving compressor section 107. Recesses 123Aare formed almost uniformly on the mutual sealing faces of port 528 andsealing section 525A of valve 525. Recesses 123B are formed almostuniformly on arm section 525B of valve 525. Recesses 123A are formedalmost uniformly on striking section 541A of valve 525 and strikingsection 541B of stopper 537. Both of striking sections 541A and 541B arethe contact sections which are brought into contact with each other bydriving compressor 107. Preferable status of recesses 123A, 123B aresimilar to what is discussed previously, and a method of forming them isalso similar to the previous one.

An operation of the compressor discussed above is demonstrated here.Commercial power is supplied to motor section 106 as a driver, therebyspinning rotor 105 of motor section 106. Rotor 105 rotates crankshaft108, and eccentric movement of eccentric section 110 drives piston 115via connecting rod 118 of the coupling section and piston-pin 117.Piston 115 thus reciprocates in bore 113. Refrigerant gas 102 guidedthrough suction tube 121 into container 101 is sucked from suctionmuffler 122 via suction valve device 527 and compressed continuously incompressing room 116. Compressed refrigerant gas 102 travels throughdischarging valve device 534 and head 120 and is discharged from adischarging pipe (not shown) to heat exchanger 70 that is a highpressure side of the refrigerating cycle.

Refrigerant gas 102 compressed continuously in compressing room 116includes a little amount of oil 103 in misting state. Refrigerant gas102 thus supplies oil 103 to the mutual sealing faces of port 528 andsealing section 525A of valve 525, and to the mutual sealing faces ofstriking section 541A of valve 525 and striking section 541B of stopper537. Oil 103 supplied there works as sealing and lubricating the mutualsealing faces and as lubricating striking sections 541A, 541B.

When recesses 123A are formed, the surface structures of port 528, valve525, striking sections 541A, 541B are undergone martensitic process, sothat the surface strength thereof are increased. Thus the abrasionresistance and impact resistance are increased. The formation ofrecesses 123A reduces the area between the contact sections, so thatmetal contacts are reduced.

Piston 115 reciprocates in bore 113 to suck and compress refrigerant gas102. At that time, parts of gas 102 discharged from discharging valvedevice 534 to head 120 leak from the mutual sealing face of dischargingvalve device 534 to compressing room 116. Refrigerant gas 102 leakingexpands again, thereby lowering the volumetric efficiency. However, inthis embodiment, oil 103 remains in recesses 123A formed almostuniformly on the mutual sealing faces of port 528 and sealing section525A of valve 525 that form discharging valve device 534. Oil 103resists against refrigerant gas 102 discharged to head 120 and leakingto compressing room 116. The spherical shape of recess 123A increasesthe volume comparing with a polygonal pyramid having the same areaprojected to the surface, so that an amount of oil 103 remainingincreases. As a result, an amount of leakage of refrigerant gas 102decreases, and the volumetric efficiency of the compressor increases, sothat the compression efficiency of the compressor increases.

Oil 103 remaining in recesses 123A contributes to increasing thelubrication on the mutual sealing faces of port 528 and sealing section525A of valve 525, so that the abrasion resistance of discharging valvedevice 534 increases.

Oil 103 remaining in recesses 123A damps an impact when sealing section525A of valve 525 is seated on port 528, so that it can lower the noisesof the compressor caused by the impact due to the seating in valvedevice 534. When recesses 123B are formed on arm 525B, residual stressof compression is applied to make the surface martensitic, so that thesurface hardness increases and the impact resistance also increases. Asa result, the strength against fatigue fracture increases.

Oil 103 also remains in recesses 123A formed almost uniformly onstriking section 541A of valve 525 and striking section 541B of stopper537. Oil 103 remaining there increase the lubrication at strikingsections 541A, 541B, so that the abrasion resistance of dischargingvalve device 534 increases.

Oil 103 remaining in recesses 123A works as a damper against an impactwhen valve 525 opens and crashes to stopper 537. This damper lowers thenoises of the compressor due to the open-impact in discharging valvedevice 534. The martensitic surface increases its own hardness and theimpact resistance.

Recesses 123A are provided to all of port 528 and sealing section 525Aof valve 525, striking sections 541A and 541B; however, recesses 123Acan be provided to either one of the combination. Recesses 123B areprovided to both faces of arm 525B of valve 525; however, they can beprovided to either one face.

Next, a discharging valve device having back-up lead 535 isdemonstrated. FIG. 41 shows a vertical sectional view of anotherdischarging valve device 534A in accordance with the embodiment of thepresent invention. FIG. 42 shows a plan view illustrating strikingsection 541C side of backup lead 535 of discharging valve device 534Aagainst discharging movable valve (valve) 525. FIG. 43 shows a plan viewillustrating striking section 541D side of back-up lead 535 ofdischarging valve device 534A against stopper 537.

Discharging valve device 534A shown in FIG. 41 has backup lead 535between valve 525 and stopper 537. Striking section 541A of valve 525and striking section 541C of backup lead 535, striking section 541D ofbackup lead 535 and striking section 541B of stopper 537 are contactsections which are brought into contact with each other by drivingcompressor section 107. Recesses 123A are formed almost uniformly onstriking sections 541C and 541D of backup lead 535. The preferable stateof recesses 123A is discussed previously, and the method of formingrecesses 123A is the same as the one discussed previously. Thestructures other than what is discussed above remain unchanged fromdischarging valve device 534 shown in FIG. 36.

An operation of the foregoing compressor is demonstrated hereinafter.Commercial power is supplied to motor section 106, thereby spinningrotor 105 of motor section 106. Rotor 105 rotates crankshaft 108, andeccentric movement of eccentric section 110 drives piston 115 viaconnecting rod 118 of the coupling section and piston-pin 117. Piston115 thus reciprocates in bore 113. Refrigerant gas 102 guided throughsuction tube 121 into container 101 is sucked from suction muffler 122via suction valve device 527 and is compressed continuously incompressing room 116. Compressed refrigerant gas 102 travels throughdischarging valve device 534A and head 120 and is discharged from adischarging pipe (not shown) to heat exchanger 70 that is a highpressure side of the refrigerating cycle.

Refrigerant gas 102 compressed continuously in compressing room 116includes a little amount of oil 103 in misting state. Compressed gas 102thus supplies oil 103 to striking section 541A of valve 525 that formsdischarging valve device 534A, to striking section 541C of backup lead535, to striking section 541D of backup lead 535, and to strikingsection 541B of stopper 537 for lubricating those striking sections.

When recesses 123A are formed, respective surface structures of strikingsection 541A of valve 525, striking section 541C of backup lead 535,striking section 541D of backup lead 535, and striking section 541B ofstopper 537 become martensitic, so that the surface strength increases.Thus the abrasion resistance and impact resistance of them increase. Theformation of recesses 123A reduces the area between the contactsections, so that metal contacts is reduced.

The spherical shape of recess 123A increases the volume comparing with apolygonal pyramid having the same area projected to the surface, so thatan amount of oil 103 remaining increases. Oil 103 remaining in recesses123A contributes to increment of the lubrication on valve 525 andstriking sections 541A, 541C of backup lead 535, and on backup lead 535and striking sections 541D, 541B of stopper 537. As a result, theabrasion resistance of discharging valve device 534 improves. Oil 103remaining in recesses 123A works as a damper when valve 525 crashes tobackup lead 535, or backup lead 535 crashes to stopper 537, so that thenoises of the compressor due to the open-impact in discharging valvedevice 534A are reduced. Further, the martensitic surface increases itshardness, and the impact resistance of respective contact sectionsincreases.

Recesses 123A are provided to all of port 528 and sealing section 525Aof valve 525, striking sections 541A and 541C, striking sections 541Dand 541B; however, recesses 123A can be provided to either element ofthe combination.

The present embodiment proves that the abrasion resistance, impactresistance, and the strength against fatigue fracture increase in thesuction valve device and the discharging valve device. The embodimentalso proves that the compressing efficiency of the compressor increases,and the noises of the compressor are lowered.

Exemplary Embodiment 6

The compressor in accordance with this exemplary embodiment hasbasically a similar structure to that shown in FIG. 1 described in thefifth embodiment. This compressor of this embodiment differs from thatof the fifth embodiment in suction valve device 527 provided to valveplate 119 and respective contact sections in discharging valve device534.

First, the suction valve device is described. FIG. 44 shows a plan viewillustrating suction valve port (port) 517 of another suction valvedevice 527 shown in FIG. 33. FIG. 45 shows a plan view illustratingsuction movable valve (valve) 519 of suction valve device 527. In thefifth embodiment previously discussed, port 517 and sealing section 519Aof valve 519, both are contact sections, have fine recesses 123A.However, in this embodiment, mixed layer 323, to which molybdenumdisulfide (MoS₂) is bound, is formed. The structures other than thisremain unchanged from the suction valve device in accordance with thefifth embodiment.

The method of forming mixed layer 323 on port 517 and valve 519 issimilar to that demonstrated in the third embodiment. The method ofcrashing the fine particles of MoS₂ to the surface, in particular,produces heat energy at the crashing, and the heat energy melts parts ofMoS₂ into the base material for producing metallic bond, thereby formingmixed layer 323. At the same time, the impact in crashing forms finerecesses in a similar way to what is done in the third embodiment. Atthat time, the structure of the surface layer becomes martensitic, sothat port 517 and valve 519 increase their surface strength. In the caseof using a leaf spring, of which surface structure is martensitic, as amaterial of valve 519, the fine recesses can be formed in a similar way.

As discussed above, port 517 and sealing section 519A of valve 519,those are elements of suction valve device 527, have mixed layer 323, towhich MoS₂ is bound. The self-lubricating function of MoS₂ lowers thefriction coefficient of mutual sealing faces of port 517 and sealingsection 519A, thereby increasing the abrasion resistance. A purity ofMoS₂ is set at not lower than 98%, so that amounts of impurity materialshaving high friction coefficients are suppressed as much as possible. Asa result, the more effective advantage is obtainable. Formation of thefine recesses almost uniformly on the surface of mixed layer 323 allowsoil 103 to remain in the recesses, and a similar advantage to thatobtained in the fifth embodiment is obtainable. In this case, apreferable state of the fine recesses is similar to that discussed inthe fifth embodiment.

This embodiment, as discussed above, proves that the formation of mixedlayer 323 on port 517 and sealing section 519A of valve 519 increasesthe abrasion resistance of suction valve device 527 of the compressor.Further, the formation of fine recesses uniformly on the surface ofmixed layer 323 increases the impact resistance of suction valve device527, and improves the performance as well as the efficiency of thecompressor. Noises due to suction valve device 527 can be lowered.

In this embodiment, mixed layer 323 is provided to both of port 517 andsealing section 519A of valve 519; however, it can be provided to eitherone. Similar to the fifth embodiment, the fine recesses can be providedto at least one of the faces of arm 519B of valve 519.

Next, a discharging valve device is described. FIG. 46 shows a plan viewillustrating discharging valve port (port) 528 of another dischargingvalve device 534 shown in FIG. 36. FIG. 47 shows a plan viewillustrating the mutual sealing face side of discharging movable valve(valve) 525 of discharging valve device 534. FIG. 48 shows a plan viewillustrating the striking section 541A side of valve 525 of dischargingvalve device 534. FIG. 49 shows a plan view illustrating stopper 537 ofdischarging valve device 534.

In the fifth embodiment, fine recesses 123A are provided to the contactsections, namely, port 528, sealing section 525A of valve 525, andstriking sections 541A, 541B. In the present embodiment, on the otherhand, mixed layer 323 to which MoS₂ is bound is formed. The structuresother than this remain unchanged from the discharging valve device inaccordance with the fifth embodiment.

The method of forming mixed layer 323 on port 528 and valve 525, andstriking sections 541A, 541B is similar to that demonstrated in thethird embodiment. The method of crashing the fine particles of MoS₂ tothe surface, in particular, produces heat energy at the crashing, andthe heat energy melts parts of MoS₂ into the base material for producingmetallic bond, thereby forming mixed layer 323. At the same time, theimpact at the crash forms fine recesses in a similar way to what is donein the third embodiment. In this case, the structure of the surfacelayer becomes martensitic, so that port 528 and valve 525, and strikingsections 541A, 541B increase their surface strength. In the case ofusing a leaf spring, of which surface structure is martensitic, as amaterial of valve 525, the fine recesses can be formed in a similar way.

As discussed above, port 528, sealing section 525A of valve 525, andstriking sections 541A, 541B, those are elements of discharging suctionvalve device 534, are equipped with mixed layer 323, to which MoS₂ isbound. The self-lubricating function of MoS₂ lowers the frictioncoefficient of mutual sealing faces of port 528 and sealing section 525Aof valve 525, and striking sections 541A, 541B, thereby increasing theabrasion resistance. The purity of MoS₂ is set at not lower than 98%, sothat amounts of impurity materials having high friction coefficients aresuppressed as much as possible. As a result, the more effectiveadvantage is obtainable. Formation of the fine recesses almost uniformlyon the surface of mixed layer 323 allows obtaining a similar advantageto that obtained in the fifth embodiment is obtainable. In this case, apreferable state of the fine recesses is similar to that discussed inthe fifth embodiment.

This embodiment, as discussed above, proves that the formation of mixedlayer 323 on port 528 and sealing section 525A of valve 525, andstriking sections 541A, 541B increases the abrasion resistance ofdischarging valve device 534. Further, the formation of fine recessesuniformly on the surface of mixed layer 323 increases the impactresistance of discharging valve device 534, and improves the performanceas well as the efficiency of the compressor. Noises due to dischargingvalve device 534 can be lowered.

Mixed layer 323 is provided to all of port 528 and sealing section 525Aof valve 525, and striking sections 541A and 541B; however, it can beprovided to either one element of respective combinations. Similar tothe fifth embodiment, the fine recesses can be provided to at least oneof the faces of arm 525B of valve 525.

Next, a discharging valve device having backup lead 535 is describedhere. FIG. 50 shows a plan view illustrating the striking section 541Cside of backup lead 535 against discharging movable valve (valve) 525 ofanother discharging valve device 534A shown in FIG. 41. FIG. 51 shows aplan view illustrating the striking section 541D side of backup lead 535against stopper 537 of discharging valve device 534A.

In the fifth embodiment, fine recesses 123A are provided to contactsections of port 528 and sealing section 525A of valve 525, and strikingsections 541A and 541C, striking sections 541D and 541B. In the presentembodiment, on the other hand, mixed layer 323 to which MoS₂ is bound isformed. The structures other than this remain unchanged from thedischarging valve device in accordance with the fifth embodiment.

The method of forming mixed layer 323 on port 528 and valve 525,striking sections 541A and 541C, and striking sections 541D and 541B, issimilar to that demonstrated in the third embodiment. The method ofcrashing the fine particles of MoS₂ to the surface, in particular,produces heat energy at the crashing, and the heat energy melts parts ofMoS₂ into the base material for producing metallic bond, thereby formingmixed layer 323. At the same time, the impact in crashing forms finerecesses in a similar way to what is done in the third embodiment. Inthis case, the structure of the surface layer becomes martensitic, sothat port 528 and valve 525, striking sections 541A and 541C, strikingsections 541D and 541B increase their surface strength. In the case ofusing a leaf spring, of which surface structure is martensitic, as amaterial of valve 525, the fine recesses can be formed in a similar way.

As discussed above, port 528 and sealing section 525A of valve 525,striking sections 541A and 541C, striking sections 541D and 541B, thoseare elements of discharging valve device 534A, are provided with mixedlayer 323, to which MoS₂ is bound. The self-lubricating function of MoS₂lowers the friction coefficient of mutual sealing faces between port 528and sealing section 525A, the friction coefficients of striking sections541A and 541C, 541D and 541B, thereby increasing the abrasionresistance. The purity of MoS₂ is set at not lower than 98%, and amountsof impurity materials having high friction coefficients are suppressedas much as possible, so that the more effective advantage is obtainable.Formation of fine recesses almost uniformly on the surface of mixedlayer 323 allows obtaining a similar advantage to that obtained in thefifth embodiment is obtainable. In this case, a preferable state of thefine recesses is similar to that discussed in the fifth embodiment.

This embodiment, as discussed above, proves that the formation of mixedlayer 323 on port 528 and sealing section 525A of valve 525, strikingsections 541A and 541C, and striking sections 541D and 541B increasesthe abrasion resistance of discharging valve device 534A. Further, theformation of fine recesses uniformly on the surface of mixed layer 323increases the impact resistance of discharging valve device 534A, andimproves the performance as well as the efficiency of the compressor.Noises due to discharging valve device 534A can be lowered.

Mixed layer 323 is provided to all of port 528 and sealing section 525Aof valve 525, striking sections 541A and 541C, striking sections 541Dand 541B; however, it can be provided to either one element ofrespective combinations.

This embodiment proves that the abrasion resistance, impact resistance,and the strength against fatigue fracture increase in the suction valvedevice, discharging valve device. The embodiment also proves that thecompressing efficiency of the compressor increases, and the noises ofthe compressor is lowered.

In the fifth and sixth embodiments, a reciprocating compressor havinginterior oil 103 is described; however, a similar advantage isobtainable with other compressors such as a rotary compressor, scrollcompressor, linear compressor. In the case of compressors, which use nooil, such as a linear compressor, an advantage involving no oil isobtainable. For instance, the abrasion resistance, impact resistance,and fatigue-fracture resistance increase because of the improvement inhardness and strength against fatigue fracture.

Exemplary Embodiment 7

FIG. 52 shows a sectional view of a refrigerant compressor in accordancewith a seventh exemplary embodiment of the present invention. FIG. 53shows a refrigerating cycle of the refrigerator including the compressorshown in FIG. 52. FIG. 54 shows an enlarged view of a contact sectionbetween a discharging path and a coil spring of the compressor shown inFIG. 52.

Closed container (container) 101 pools oil 103, accommodates motorsection 106 having stator 104 and rotor 105 as well as reciprocatingcompressor section 107 driven by motor section 106. Discharging path 717is provided for guiding the compressed refrigerant gas from compressingroom 107 to the outside of container 101. Discharging path 717 made fromsteel pipe is closely surrounded with cohesive coil spring (spring) 718for preventing abnormal vibration due to resonance. Spring 718 works asa resonance preventive section which can be also made from elasticmaterial such as rubber.

Crankshaft 108 has main shaft 109, to which rotor 105 is press-fitted,and eccentric section 110 eccentric with respect to main shaft 109, andhas lubricating pump 111. Cylinder block 112 includes compressing room116 having typically cylindrical bore 113. Piston 115 reciprocating inbore 113 is coupled to eccentric section 110 via a coupling section,i.e. connecting rod 719. An end face of bore 113 is sealed by valveplate 119.

Head 120 forms a high-pressure room, and discharging path 717 is coupledto heat exchanger 70, i.e. a high pressure side of the refrigeratingcycle, via container 101. Discharging path 717 guides the compressedrefrigerant gas from head 120 to the outside of container 101.

On the surface of discharging path 717, fine recesses (hereinafterreferred to simply as recesses) 123 are formed almost uniformly.Recesses 123 are preferably spherical and have a diameter of 2-20 μm, adepth of 0.2-1.0 μm. Further, the recesses on contact face 717A betweenspring 718 and discharging path 717 preferably accounts for 40-80% ofthe surface area of face 717A.

The method of forming recesses 123 is similar to the method discussed inthe first embodiment.

The refrigerant gas is hydrocarbon refrigerant including no chlorine,and oil 103 is mutually soluble with this refrigerant.

An operation of the foregoing compressor is demonstrated hereinafter.Rotation of crankshaft 108 accompanies the linear motion of piston 115,thereby changing a volume of compressing room 116. The refrigerant gas(not shown) is thus compressed, and guided to the outside of container101 via discharging path 717, then the gas arrives at heat exchanger 70,where the gas dissipates its heat to the outside, and returns to heatexchanger 60 via expansion valve 80. The refrigerating machine is thusstructured.

The rotation of crankshaft 108 prompts lubricating pump 111 to supplyoil 103 to respective sliding sections for lubrication, and then oil 103is discharged from a tip of eccentric section 110 into container 101.Oil 103 is also discharged to discharging path 717.

Compressor unit 707 always generates micro-vibration while compressorsection 107 operates, and at the start or stop of the operation,compressor unit 707 largely wobbles due to inertia force, thendischarging path 717 wobbles in every direction, so that spring 718contacts the steel pipe of discharging path 717 intermittently. As such,they are contact sections scraping against each other caused by drivingcompressor section 107.

However, in this embodiment, as shown in FIG. 54, recesses 123 areformed almost uniformly on contact face 717A of discharging path 717.The formation of recesses 123 reduces the area between the contactsections, so that metal contacts can be reduced. At the formation ofrecesses 123, the surface structure of discharging path 717 and spring718 becomes martensitic, and thus the surface strength increases, sothat the abrasion resistance and impact resistance of those surfacesincrease. Oil 103 retained in recesses 123 is drawn into the spacebetween discharging path 717 and spring 718 when this space becomessmaller due to the relative motion between the viscosity of oil 103 andthe contact sections. Pressure which bears the load occurs in oil 103,thereby forming wedge-shaped oil film, which prevents the metal contactsfrom happening on contact face 717A, so that abnormal noises can beeffectively suppressed.

Spherical recesses 123 will produce a flow of oil 103, as shown in FIG.3 discussed in the first embodiment, thereby generating oil pressure,which prevents the metal contacts and thus the abnormal noises fromhappening.

The size of each one of recesses 123 is set as diameter of 20-50 μm,depth of 1-10 μm, so that the volume of each recess 123 is determinedsmall. The volumetric change at the supply of oil 103 including therefrigerant to recesses 123 becomes thus small. As a result, littledecrease in the pressure at the space between the contact sections isexpected. Foaming phenomenon of the refrigerant dissolving in oil 103can be observed thus only a little, so that breakage of the oil film dueto the foaming of refrigerant happens little, and the function ofpreventing the metal contacts is kept at a high level. As a result, theabrasion resistance increases, and the function of preventing theabnormal noises is boosted.

If the recesses accounts for 40-80% of the surface area of sliding face717A, the spherical shape of recess 123 can be maintained. As a result,a slant surface due to recess 123 is provided uniformly between path 717and spring 718, and a flat area is provided uniformly in parallel withsliding face 717A. In other words, an effect similar to that of ataper-land bearing is obtainable. This structure boosts the dynamicpressure produced in sliding, so that the metal contacts can be furtherprevented.

When recesses 123 are formed on the surface of the steel pipe, i.e. anelement of discharging path 717, steel balls or ceramic balls arecrashed to the surface at a speed higher than a given one. The surfacestructure of pipe 717 thus becomes martensitic, so that the surfacehardness increases, and the abrasion resistance increases.

Hydrocarbon refrigerant is used as the refrigerant gas which is highlymutually soluble with oil 103; however the refrigerant dissolving in oil103 produces foams little as discussed previously. The oil film is thusscarcely broken by the foams, so that the abrasion resistance increasesand the abnormal noises can be prevented in addition to suppressingozonosphere and global warming. Those advantages contribute to thereduction of the number of components and the manufacturing cost of thecompressor.

Exemplary Embodiment 8

FIGS. 55A and 55B show enlarged views of a contact section between adischarging path and a coil spring of the compressor in accordance withan eighth exemplary embodiment of the present invention. This compressorhas a similar structure to that demonstrated in the seventh embodimentusing FIG. 52. This compressor has mixed layer 323 including molybdenumdisulfide (MoS₂) on the surface of a steel pipe which forms dischargingpipe 717 as shown in FIG. 55A, while the steel pipe of path 717 in theseventh embodiment has fine recesses 123 formed almost uniformly on itssurface. The structures other than this remain unchanged from thecompressor of the seventh embodiment.

As shown in FIG. 55B, recesses 123 are preferably formed almostuniformly on mixed layer 323, and each one of recesses 123 is preferablyshaped spherically, and has a diameter of 2-20 μm and a depth of 0.2-1.0μm. The recesses preferably accounts for 40-80% of the surface area ofthe contact face 717A between spring 718 and discharging path 717.

The methods of forming mixed layer 323 and recesses 123 are similar tothose discussed in the third embodiment.

The refrigerant gas is made of hydrocarbon refrigerant, which includesno chlorine and is mutually soluble with oil 103.

Compressor unit 707 always generates micro-vibration while compressorsection 107 operates, and at the start or stop of the operation,compressor unit 707 largely wobbles due to inertia force, thendischarging path 717 wobbles in every direction, so that spring 718contacts the steel pipe of discharging path 717 intermittently. As such,they are contact sections scraping against each other caused by drivingcompressor section 107.

However, in this embodiment, mixed layer 323 including MoS₂ is formed oncontact surface 717A of discharging path 717. Because the structure ofMoS₂ forms dense hexagonal system, when solid contacts happen, the MoS₂cleaves at a low friction coefficient, thereby exerting itsself-lubricating function. The friction coefficient at the contactsections is thus lowered, and abnormal noises due to metal contacts areeffectively suppressed.

The purity of MoS₂ is preferably set at not lower than 98%, so that theamounts of impurities having high friction coefficients decrease tolittle amounts, thereby lowering the friction coefficient andsuppressing effectively the abnormal noises caused by metal contacts.

The purity of MoS₂ is preferably set at not lower than 98%, so thatamounts of impurity materials having high friction coefficients aresuppressed as much as possible, thereby further lowering the frictioncoefficient and suppressing the abnormal noises caused by metalcontacts.

As shown in FIG. 55B, the formation of recesses 123 almost uniformly oncontact face 725 of mixed layer 323 produces a similar advantage to thatdiscussed in the seventh embodiment.

The preferable state of recesses 123 is similar to that discussed in theseventh embodiment. Balls of MoS₂ are crashed to the surface ofdischarging path 717 made of steel pipe at a speed higher than a givenone for producing recesses 123, so that the surface structure ofdischarging path 717 becomes martensitic, and the surface hardnessincreases as well as the abrasion resistance increases.

Hydrocarbon refrigerant is used as the refrigerant gas which is highlymutually soluble with oil 103; however the refrigerant dissolving in oil103 produces foams little as discussed above. The oil film is thusscarcely broken by the foams, so that the abrasion resistance increasesand the abnormal noises can be prevented in addition to suppressingozonosphere and global warming. Those advantages contribute to thereduction of the number of components and the manufacturing cost of thecompressor.

In the seventh and eighth embodiments, the compressor is demonstrated asa reciprocating compressor. A rotary compressor or a linear compressor,which has a path for guiding the refrigerant gas from the compressingmechanism to the outside of the container, can obtain a similaradvantage to what is discussed above.

Exemplary Embodiment 9

A compressor in accordance with the present exemplary embodiment has asimilar structure to that demonstrated in the seventh embodiment usingFIG. 52. This compressor differs from that one demonstrated in theseventh embodiment in the structure of supporting section 923 whichresiliently supports compressor section 107 via stator 104 in closedcontainer(hereinafter referred to simply as “container”) 101. FIG. 56shows a sectional view of the refrigerant compressor in accordance withthis exemplary embodiment. FIG. 57A shows an enlarged view illustratinga contact section between compression coil spring 908 and holder 922 insupporting section 923.

Stator fastening bolt 919 for fastening stator 104 of motor section 106has holder 920 integrally formed therewith at its head. Container 101has holder 922 fixed to its bottom of the inner wall. Compression coilspring (hereinafter referred to simply as “spring”) 908 has its upperend and lower end inserted into holders 920 and 922 respectively.Supporting section 923 is formed of spring 908, holders 920 and 922.

Spring 908, holders 920, 922 are made from iron-based metal material.Fine recesses (hereinafter referred to simply as “recesses”) 123 areformed almost uniformly on at least one of the mutual contact facesbetween spring 908 and holder 920, between spring 908 and holder 922.FIG. 57A shows an example of fine recesses 123 formed on contact face924 of holder 922.

Recesses 123 are preferably spherical and have a diameter of 2-20 μm, adepth of 0.2-1.0 μm. Further, the recesses preferably accounts for40-80% of the mutual sealing surface area.

The method of forming recesses 123 on spring 908, holder 920, 922 issimilar to the method discussed in the first embodiment.

The refrigerant gas is made of hydrocarbon refrigerant free fromchlorine and is mutually soluble with oil 103.

An operation of the compressor structured above is demonstratedhereinafter. Rotation of crankshaft 108 accompanies the linear motion ofpiston 115, thereby changing a volume of compressing room 116. Therefrigerant gas (not shown) is thus compressed, and guided to theoutside of container 101 via discharging path 717. The rotation ofcrankshaft 108 prompts lubricating pump 111 to supply oil 103 torespective sliding sections for lubrication, and then oil 103 isdischarged from a tip of eccentric section 110 into container 101.

Compressor unit 707 always generates micro-vibration while compressorsection 107 operates, and at the start or stop of the operation,compressor unit 707 largely wobbles due to inertia force, then spring908 wobbles in every direction, so that spring 908 contacts holders 920,922 intermittently. As such they are contact sections scraping againsteach other caused by driving compressor section 107.

However as shown in FIG. 57A, recesses 123 are formed almost uniformlyon contact face 924 of holder 922. The formation of recesses 123 reducesthe area between the contact sections, so that metal contacts arereduced. At the formation of recesses 123, the surface structure ofholder 922 becomes martensitic, and thus the surface strength increases,so that the abrasion resistance and impact resistance of holder 922increase. In order to work these advantages more explicitly, recesses123 are preferably formed on every contact faces of spring 908, holders920, 922.

The formation of recesses 123 on the mutual contact faces such ascontact face 924 allows recesses 123 to retain oil 103. Oil 103 is drawninto the spaces between spring 908 and holder 920, between spring 908and holder 922 when those spaces become smaller, because of the relativemotion between the viscosity of oil 103 and the contact sections.Pressure which bears the load thus occurs in oil 103, thereby formingwedge-shaped oil film, which prevents the metal contacts from happeningon the mutual contact faces, so that abnormal noises are effectivelysuppressed.

The spherical shape of recess 123 allows the flow of oil, whichgenerates oil film at the sliding, to produce a vertex flow in recess123 with ease. This phenomenon is similar to what is discussed in thefirst embodiment using FIG. 3. Thus an oil pressure is generated, whichprevents the metal contact as well as abnormal sound.

The preferable state of recesses 123 is similar to that described inother embodiments, so that it is omitted here. The preferable stateincludes a size of each one of recesses 123 and a percentage of therecessed area occupying the surface area of the contact sections.

Hydrocarbon refrigerant is used as the refrigerant gas which is highlymutually soluble with oil 103; however the refrigerant dissolving in oil103 produces foams little as discussed previously. The oil film is thusscarcely broken by the foams. The hydrocarbon refrigerant free fromchlorine is used, so that even in the open air, both of the ozonosphereand global warming are suppressed in addition to the advantages such asthe increase in abrasion resistance and the prevention of abnormalsound. Those advantages contribute to the reduction of the number ofcomponents and the manufacturing cost of the compressor.

As shown in FIG. 57B, mixed layer 323 to which MoS₂ is bound can beformed on the mutual contact faces, such as contact face 924. The methodof forming MoS₂ on the contact faces is similar to that discussed in thethird embodiment. This structure allows the MoS₂ to cleave at a lowfriction coefficient and exerts its solid self-lubrication function evenif solid contact happens. The friction coefficient of the contactsection thus lowers, and abnormal sound due to metal contact iseffectively suppressed. The purity of MoS₂ is similar to that describedin the third embodiment.

As shown in FIG. 57C, recesses 123 shown in FIG. 57A can be formedalmost uniformly on the surface of mixed layer 323. The method offorming mixed layer 323 and recesses 123 simultaneously is similar tothat described in the third embodiment. The preferable state of recesses123 is described previously. This structure allows exerting theadvantages demonstrated using FIGS. 57A and 57B in a compound manner.

In this embodiment, holders 920 and 922, and spring 908 disposedtherebetween form supporting section 923, namely, the coil-springsuspension method is employed. Other than this method, the leaf-springmethod or the torsion-bar method can be used to form supporting section923. In those cases, the formation of recesses 123 or mixed layer 323 ona section slid by driving compressor section 107 can produce a similaradvantage to that discussed previously.

In this embodiment, a refrigerating machine employing a reciprocatingcompressor is used; however, any refrigerating machines can obtain asimilar advantage as far as they employ an inner suspension methodregardless of types or models, such as rotary compressor, scrollcompressor, linear compressor, or starling-pump.

INDUSTRIAL APPLICABILITY

The refrigerant compressor of the present invention includes acompressor section, a driver, a first contact section and a secondcontact section. The compressor section is accommodated in a closedcontainer for compressing the refrigerant gas. The driver drives thecompressor section. The first and second contact sections are broughtinto contact with each other or they slide with each other by drivingthe compressor section. On the surface of each one of the contactsections, at least one of plural recesses uniformly placed or a mixedlayer, to which molybdenum disulfide (MoS₂) is bound, is formed. Thosecontact sections refer to the following elements: sliding sections of apiston and a bore, a valve port and a movable valve of a suction valveor a discharging valve, a steel pipe and a coil spring of a dischargingpath, holders and a spring forming the supporting section for supportingthe compressor section and so on. This structure allows increasing theabrasion resistance of the first and second contact sections, so that areliable and efficient compressor is obtainable. The refrigeratingmachine employing such a compressor is also reliable and efficient.

1. A refrigerant compressor comprising: a closed container; a compressorsection, which is accommodated in the closed container, for compressingrefrigerant; a driver for driving the compressor section; and aplurality of contact sections including first contact section and asecond contact section to be brought into contact with each other orslid with each other by driving the compressor section, wherein at leastone of a plurality of spherically shaped recesses is formed on a surfaceof at least one of the first contact section and the second contactsection, and wherein the at least one spherically shaped recess is (a)shaped sufficiently for causing a distance between the contact sectionsto remain constant as the contact sections move with respect to eachother and (b) configured for causing oil to form a vortex flow in theone spherically shaped recess and the oil is retained in the at leastone recess.
 2. The refrigerant compressor of claim 1, wherein the firstcontact section and the second contact section are sliding componentsforming the compressor section.
 3. The refrigerant compressor of claim1, wherein the compressor section has a piston and a bore in which thepiston is loosely fitted, wherein the first contact section refers tothe piston, and the second contact section refers to the bore.
 4. Therefrigerant compressor of claim 1, wherein the compressor section has acrankshaft including a main shaft and an eccentric section, and abearing for supporting the main shaft, wherein the first contact sectionrefers to the main shaft, and the second contact section refers to thebearing.
 5. The refrigerant compressor of claim 1, wherein thecompressor section has: a crankshaft including a main shaft and aneccentric section; a piston; a piston-pin disposed at the piston; and aconnecting rod for coupling the eccentric section to the piston-pin,wherein the first contact section refers to the piston-pin, and thesecond contact section refers to the connecting rod.
 6. The refrigerantcompressor of claim 1, wherein the driver has a rotor, wherein thecompressor section has a crankshaft including a main shaft and aneccentric section, and a bearing for supporting the main shaft, whereinthe refrigerant compressor further comprises a thrust washer disposedbetween the rotor and the bearing, wherein the rotor has a flange facecontacting the thrust washer, wherein the bearing has a thrust sectioncontacting the thrust washer, and wherein the first contact sectionrefers to the thrust washer, and the second contact section refers to atleast one of the flange face and the thrust face.
 7. The refrigerantcompressor of claim 1, wherein the compressor section has: a crankshaftincluding: a main shaft; an eccentric section; a flange section disposedbetween the main shaft and the eccentric section, a bearing, forsupporting the main shaft, including a thrust section contacting theflange section, wherein the first contact section refers to the flangesection, and the second contact section refers to the thrust section. 8.The refrigerant compressor of claim 1, wherein the compressor sectionhas: a compressing room; a rolling piston for rolling in the compressingroom; and a vane for being pushed by the rolling piston to partition thecompressing room, wherein the first contact section refers to therolling piston, and the second contact section refers to the vane. 9.The refrigerant compressor of claim 1, wherein the compressor sectionhas: a shaft including a main shaft, a sub-shaft, and an eccentricsection; a rolling piston loosely fitted in the eccentric section; amain bearing for supporting the main shaft; and a sub-bearing forsupporting the sub-shaft, wherein a combination of the first contactsection and the second contact section refers to at least one of acombination of the eccentric section and the rolling piston, acombination of the main shaft and the main bearing, and a combination ofthe sub-shaft and the sub-bearing.
 10. The refrigerant compressor ofclaim 1, wherein the compressor section has at least one of: a suctionvalve device including a suction valve port and a suction movable valve,wherein the suction movable valve opens during a sucking operation; anda discharging valve device including a discharging valve port and adischarging movable valve, wherein the discharging movable valve opensduring a discharging operation, wherein a combination of the firstcontact section and the second contact section refers to at least one ofa combination of the suction valve port and the suction movable valve,and a combination of the discharging valve port and the dischargingmovable valve.
 11. The refrigerant compressor of claim 10, wherein atleast one of the suction movable valve and the discharging movable valveis formed of a leaf spring having martensitic surface structure.
 12. Therefrigerant compressor of claim 10, wherein at least one of the suctionmovable valve and the discharging movable valve has an arm of which atleast one of faces has recesses formed uniformly.
 13. The refrigerantcompressor of claim 10, wherein the discharging movable valve has afirst striking section, wherein the discharging valve device further hasa stopper, for regulating a motion of the discharging movable valve, andwhich stopper has a second striking section which is brought intocontact with the first striking section by an opening operation of thedischarging movable valve, wherein the first contact section refers tothe first striking section, and the second contact section refers to thesecond striking section.
 14. The refrigerant compressor of claim 13,wherein the discharging valve device further has a backup lead disposedbetween the stopper and the discharging movable valve, the backup leadhaving a third striking section and a fourth striking section, wherein acombination of the first contact section and the second contact sectionrefers to at least one of a combination of the first striking sectionand the third striking section, and a combination of the second strikingsection and the fourth striking section.
 15. The refrigerant compressorof claim 1 further comprising a discharging path for guiding thecompressed refrigerant from the compressor section to outside of theclosed container; and a resonance preventive section which covers thedischarging path, wherein the first contact section refers to thedischarging path, and the second contact section refers to the resonancepreventive section.
 16. The refrigerant compressor of claim 1 furthercomprising a supporting section, for resiliently supporting thecompressor section in the closed container, which supporting section hasthe first contact section and the second contact section.
 17. Therefrigerant compressor of claim 16, wherein the supporting section has:a first holder for holding the compressor section; a second holderdisposed on an inner wall of the closed container; and a spring disposedbetween the first holder and the second holder; wherein the firstcontact section refers to the spring, and the second contact sectionrefers to at least one of the first holder and the second holder. 18.The refrigerant compressor of claim 1 further comprising oil whichremaining one of in the recesses and on a surface of the mixed layer.19. The refrigerant compressor of claim 18, wherein the recesses havespherical surfaces.
 20. The refrigerant compressor of claim 18, whereinthe recesses have a diameter of at least 2 μm and at most 50 μm, and adepth of at least 0.5 μm and at most 10 μm.
 21. The refrigerantcompressor of claim 18, wherein an area occupied by the recessesaccounts for at least 40% and at most 80% of a surface area of at leastone of the first contact section and the second contact section on whichthe recesses are formed.
 22. The refrigerant compressor of claim 18,wherein a viscosity of the oil is at least VG5 and less than VG10. 23.The refrigerant compressor of claim 18, wherein the refrigerant is madefrom hydrocarbon free from chlorine and the oil is mutually soluble withthe refrigerant.
 24. The refrigerant compressor of claim 18, wherein therefrigerant includes at least one of isobutane and propane, and whereinthe oil includes at least one of alkylbenzene, mineral oil, ester,polyvinylether and polyalkyleneglycol.
 25. The refrigerant compressor ofclaim 1, wherein the first contact section and the second contactsection are made of iron-based base material, and a surface structure ofat least one of the first contact section and the second contact sectionis martensitic.
 26. The refrigerant compressor of claim 1, wherein apurity of the molybdenum disulfide of the mixed layer is at least 98%.27. The refrigerant compressor of claim 1, wherein the recesses isformed on surfaces of the mixed layer.
 28. The refrigerant compressor ofclaim 1, wherein the plurality of recesses are spaced from each othersufficiently for forming oil uniformly between the contact sections.